Add Muzi Base board support (Duo + Uno + SuperIO)

One nRF52840 variant shared across both radios, picked per env: Duo runs
the LR1121, Uno the SX1262. Same PCB, only the radio and its DIO1 pin
change.

SuperIO adds the SH1107 OLED, GPS, buzzer and joystick. GPS is driven by
the 3-position mode switch (Mode 2 = on), polled live the way thinknode_m1
does it.

Five quick user-button presses power the unit off; a press wakes it back
on (arms the button as an nRF52 GPIO SENSE source before SYSTEMOFF).

Consolidates #2054 and andyshinn's shared-base/uno work, rebased on dev.

Co-authored-by: lbibass <ewdries02@gmail.com>
Co-authored-by: Andy Shinn <andys@andyshinn.as>

variants/muzi_base/variant.cpp

@@ -0,0 +1,90 @@
+/*
+ * variant.cpp
+ * Copyright (C) 2023 Seeed K.K.
+ * MIT License
+ */
+
+#include "variant.h"
+#include "wiring_constants.h"
+#include "wiring_digital.h"
+
+const uint32_t g_ADigitalPinMap[PINS_COUNT + 1] =
+{
+    0,
+    1,
+    2,
+    3,
+    4,
+    5,
+    6,
+    7,
+    8,
+    9,
+    10,
+    11,
+    12,
+    13,
+    14,
+    15,
+    16,
+    17,
+    18,
+    19,
+    20,
+    21,
+    22,
+    23,
+    24,
+    25,
+    26,
+    27,
+    28,
+    29,
+    30,
+    31,
+// P1 pins.
+    32,
+    33,
+    34,
+    35,
+    36,
+    37,
+    38,
+    39,
+    40,
+    41,
+    42,
+    43,
+    44,
+    45,
+    46,
+    47,
+};
+
+void initVariant()
+{
+  // All pins output HIGH by default.
+  // https://github.com/Seeed-Studio/Adafruit_nRF52_Arduino/blob/fab7d30a997a1dfeef9d1d59bfb549adda73815a/cores/nRF5/wiring.c#L65-L69
+
+  pinMode(PIN_VBAT_READ, INPUT);
+  pinMode(PIN_BATTERY_CHARGING, INPUT);
+  pinMode(PIN_CHARGER_FAULT, INPUT);
+  pinMode(PIN_BUTTON1, INPUT);
+  pinMode(PIN_BUTTON2, INPUT);
+  pinMode(PIN_BUTTON3, INPUT);
+  pinMode(PIN_BUTTON4, INPUT);
+  pinMode(PIN_BUTTON5, INPUT);
+  pinMode(PIN_BUTTON6, INPUT);
+  pinMode(LED_PIN, OUTPUT);
+  pinMode(LED_BLUE, OUTPUT);
+  digitalWrite(LED_PIN, LOW);
+  digitalWrite(LED_BLUE, LOW);
+  pinMode(BUZZER_PIN, OUTPUT);
+  digitalWrite(BUZZER_PIN, LOW); // turn off buzzer at start. don't leave it high.
+  // gps power is driven by the sensor manager (mode switch). off to start.
+  pinMode(PIN_GPS_EN, OUTPUT);
+  digitalWrite(PIN_GPS_EN, LOW);
+
+  pinMode(SCREEN_12V_ENABLE, OUTPUT);
+  digitalWrite(SCREEN_12V_ENABLE, LOW); // disable 12V power for SH1107 display for now.
+}