chore: improve doc generation and test (#762)

Improve documentation generation and add tests for documentation.
Extend sphinx by todo directive.

The configuration table is now split into several tables. The test
is adapted accordingly.

There is a new test that checks the docstrings to be compliant to the
RST format as used by sphinx to create the documentation. We can not
use Markdown in docstrings. The docstrings are adapted accordingly.

An additional test checks that the documentation can be build with sphinx.
This test takes very long is only enabled in full run (aka. ci) mode.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

openapi.json

@@ -2519,7 +2519,7 @@
         "additionalProperties": false,
         "type": "object",
         "title": "ConfigEOS",
-        "description": "Singleton configuration handler for the EOS application.\n\nConfigEOS extends `SettingsEOS` with support for  default configuration paths and automatic\ninitialization.\n\n`ConfigEOS` ensures that only one instance of the class is created throughout the application,\nallowing consistent access to EOS configuration settings. This singleton instance loads\nconfiguration data from a predefined set of directories or creates a default configuration if\nnone is found.\n\nInitialization Process:\n  - Upon instantiation, the singleton instance attempts to load a configuration file in this order:\n    1. The directory specified by the `EOS_CONFIG_DIR` environment variable\n    2. The directory specified by the `EOS_DIR` environment variable.\n    3. A platform specific default directory for EOS.\n    4. The current working directory.\n  - The first available configuration file found in these directories is loaded.\n  - If no configuration file is found, a default configuration file is created in the platform\n    specific default directory, and default settings are loaded into it.\n\nAttributes from the loaded configuration are accessible directly as instance attributes of\n`ConfigEOS`, providing a centralized, shared configuration object for EOS.\n\nSingleton Behavior:\n  - This class uses the `SingletonMixin` to ensure that all requests for `ConfigEOS` return\n    the same instance, which contains the most up-to-date configuration. Modifying the configuration\n    in one part of the application reflects across all references to this class.\n\nAttributes:\n    config_folder_path (Optional[Path]): Path to the configuration directory.\n    config_file_path (Optional[Path]): Path to the configuration file.\n\nRaises:\n    FileNotFoundError: If no configuration file is found, and creating a default configuration fails.\n\nExample:\n    To initialize and access configuration attributes (only one instance is created):\n    ```python\n    config_eos = ConfigEOS()  # Always returns the same instance\n    print(config_eos.prediction.hours)  # Access a setting from the loaded configuration\n    ```"
+        "description": "Singleton configuration handler for the EOS application.\n\nConfigEOS extends `SettingsEOS` with support for  default configuration paths and automatic\ninitialization.\n\n`ConfigEOS` ensures that only one instance of the class is created throughout the application,\nallowing consistent access to EOS configuration settings. This singleton instance loads\nconfiguration data from a predefined set of directories or creates a default configuration if\nnone is found.\n\nInitialization Process:\n  - Upon instantiation, the singleton instance attempts to load a configuration file in this order:\n    1. The directory specified by the `EOS_CONFIG_DIR` environment variable\n    2. The directory specified by the `EOS_DIR` environment variable.\n    3. A platform specific default directory for EOS.\n    4. The current working directory.\n  - The first available configuration file found in these directories is loaded.\n  - If no configuration file is found, a default configuration file is created in the platform\n    specific default directory, and default settings are loaded into it.\n\nAttributes from the loaded configuration are accessible directly as instance attributes of\n`ConfigEOS`, providing a centralized, shared configuration object for EOS.\n\nSingleton Behavior:\n  - This class uses the `SingletonMixin` to ensure that all requests for `ConfigEOS` return\n    the same instance, which contains the most up-to-date configuration. Modifying the configuration\n    in one part of the application reflects across all references to this class.\n\nAttributes:\n    config_folder_path (Optional[Path]): Path to the configuration directory.\n    config_file_path (Optional[Path]): Path to the configuration file.\n\nRaises:\n    FileNotFoundError: If no configuration file is found, and creating a default configuration fails.\n\nExample:\n    To initialize and access configuration attributes (only one instance is created):\n    .. code-block:: python\n\n        config_eos = ConfigEOS()  # Always returns the same instance\n            print(config_eos.prediction.hours)  # Access a setting from the loaded configuration"
       },
       "DDBCActuatorStatus": {
         "properties": {
@@ -7153,7 +7153,7 @@
         },
         "type": "object",
         "title": "PydanticDateTimeData",
-        "description": "Pydantic model for time series data with consistent value lengths.\n\nThis model validates a dictionary where:\n- Keys are strings representing data series names\n- Values are lists of numeric or string values\n- Special keys 'start_datetime' and 'interval' can contain string values\nfor time series indexing\n- All value lists must have the same length\n\nExample:\n    {\n        \"start_datetime\": \"2024-01-01 00:00:00\",  # optional\n        \"interval\": \"1 Hour\",                     # optional\n        \"loadforecast_power_w\": [20.5, 21.0, 22.1],\n        \"load_min\": [18.5, 19.0, 20.1]\n    }"
+        "description": "Pydantic model for time series data with consistent value lengths.\n\nThis model validates a dictionary where:\n- Keys are strings representing data series names\n- Values are lists of numeric or string values\n- Special keys 'start_datetime' and 'interval' can contain string values\nfor time series indexing\n- All value lists must have the same length\n\nExample:\n    .. code-block:: python\n\n        {\n            \"start_datetime\": \"2024-01-01 00:00:00\",  # optional\n            \"interval\": \"1 Hour\",                     # optional\n            \"loadforecast_power_w\": [20.5, 21.0, 22.1],\n            \"load_min\": [18.5, 19.0, 20.1]\n        }"
       },
       "PydanticDateTimeDataFrame": {
         "properties": {