Initiate magnetometer based compass calibration from button presses (#5553)

* Initiate magenetometer based compass calibration from button presses

- only active for BMX160 accelerometers on RAK_4631
- replace automatic calibration on power on with button triggered
  calibration
- set 5 presses to trigger 30s calibration
- set 6 presses to trigger 60s calibration (useful if unit is not
  handheld, ie vehicle mounted)
- show calibration time remaining on calibration alert screen

* Fix non RAK 4631 builds

- exclude changes from non RAK 4631 builds
- remove calls to screen when not present

* Fix build on RAK4631_eth_gw

- exclude all compass heading updates on variant without screen

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/motion/MotionSensor.cpp

@@ -2,6 +2,8 @@
 
 #if !defined(ARCH_PORTDUINO) && !defined(ARCH_STM32WL) && !MESHTASTIC_EXCLUDE_I2C
 
+char timeRemainingBuffer[12];
+
 // screen is defined in main.cpp
 extern graphics::Screen *screen;
 
@@ -37,6 +39,12 @@ void MotionSensor::drawFrameCalibration(OLEDDisplay *display, OLEDDisplayUiState
     display->setTextAlignment(TEXT_ALIGN_LEFT);
     display->setFont(FONT_MEDIUM);
     display->drawString(x, y, "Calibrating\nCompass");
+
+    uint8_t timeRemaining = (screen->getEndCalibration() - millis()) / 1000;
+    sprintf(timeRemainingBuffer, "( %02d )", timeRemaining);
+    display->setFont(FONT_SMALL);
+    display->drawString(x, y + 40, timeRemainingBuffer);
+
     int16_t compassX = 0, compassY = 0;
     uint16_t compassDiam = graphics::Screen::getCompassDiam(display->getWidth(), display->getHeight());