Add WiFi companion support for Pico W

SerialWifiInterface has no ESP32-specific code, so move it to
helpers/wifi and reuse it on RP2040. Guard the ESP32-only WiFi
event/auto-reconnect calls and poll link state on RP2040 instead.

variants/rpi_picow/platformio.ini

@@ -81,20 +81,22 @@ lib_ignore = BLE
 ; lib_deps = ${rpi_picow.lib_deps}
 ;   densaugeo/base64 @ ~1.4.0
 
-; [env:PicoW_companion_radio_wifi]
-; extends = rpi_picow
-; build_flags = ${rpi_picow.build_flags}
-;   -D MAX_CONTACTS=100
-;   -D MAX_GROUP_CHANNELS=8
-;   -D WIFI_DEBUG_LOGGING=1
-;   -D WIFI_SSID='"myssid"'
-;   -D WIFI_PWD='"mypwd"'
-; ;  -D MESH_PACKET_LOGGING=1
-; ;  -D MESH_DEBUG=1
-; build_src_filter = ${rpi_picow.build_src_filter}
-;   +<../examples/companion_radio/*.cpp>
-; lib_deps = ${rpi_picow.lib_deps}
-;   densaugeo/base64 @ ~1.4.0
+[env:PicoW_companion_radio_wifi]
+extends = rpi_picow
+build_flags = ${rpi_picow.build_flags}
+  -D MAX_CONTACTS=100
+  -D MAX_GROUP_CHANNELS=8
+  -D WIFI_DEBUG_LOGGING=1
+  -D WIFI_SSID='"myssid"'
+  -D WIFI_PWD='"mypwd"'
+;  -D MESH_PACKET_LOGGING=1
+;  -D MESH_DEBUG=1
+build_src_filter = ${rpi_picow.build_src_filter}
+  +<helpers/wifi/*.cpp>
+  +<../examples/companion_radio/*.cpp>
+lib_deps = ${rpi_picow.lib_deps}
+  densaugeo/base64 @ ~1.4.0
+lib_ignore = BLE
 
 [env:PicoW_terminal_chat]
 extends = rpi_picow