Fix blank OLED on T-Beam Supreme V3 (I2C bus + 0x3D address)

The SH1106 OLED on the LilyGo T-Beam Supreme V3 never lights up because:

1. The primary I2C bus (Wire) that the OLED, BME280 and magnetometer share
   is never initialized. The PMU/RTC use Wire1 (via XPowersLib); nothing
   brings up Wire on PIN_BOARD_SDA/PIN_BOARD_SCL, so the display driver
   talks on the wrong default pins.
2. The OLED is at I2C address 0x3D on this board (0x3C is taken by the
   QMC6310 magnetometer), but SH1106Display::begin() only tried 0x3C.

Initialize Wire for TBEAM_SUPREME_SX1262, and have SH1106Display::begin()
prefer 0x3D (only ever used by the OLED) before falling back to 0x3C.
Backwards-compatible for boards with the OLED at 0x3C.

Closes #2609

src/helpers/esp32/TBeamBoard.cpp

@@ -16,6 +16,16 @@ void TBeamBoard::begin() {
     
     ESP32Board::begin();
 
+#ifdef TBEAM_SUPREME_SX1262
+    // On the T-Beam S3 Supreme the PMU + RTC sit on Wire1 (GPIO 42/41, brought
+    // up by XPowersLib), while the SH1106 OLED and the BME280/QMC6310 sensors
+    // sit on the primary bus, Wire (GPIO PIN_BOARD_SDA/PIN_BOARD_SCL). Nothing
+    // else initialises Wire on this board, so the display driver would
+    // otherwise talk on the wrong (default) pins and display.begin() fails,
+    // leaving the screen blank. Bring the OLED bus up here.
+    Wire.begin(PIN_BOARD_SDA, PIN_BOARD_SCL);
+#endif
+
     power_init();
 
     //Configure user button