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/ButtonThread.cpp

@@ -190,6 +190,20 @@ int32_t ButtonThread::runOnce()
             case 4:
                 digitalWrite(PIN_EINK_EN, digitalRead(PIN_EINK_EN) == LOW);
                 break;
+#endif
+#if defined(RAK_4631)
+            // 5 clicks: start accelerometer/magenetometer calibration for 30 seconds
+            case 5:
+                if (accelerometerThread) {
+                    accelerometerThread->calibrate(30);
+                }
+                break;
+            // 6 clicks: start accelerometer/magenetometer calibration for 60 seconds
+            case 6:
+                if (accelerometerThread) {
+                    accelerometerThread->calibrate(60);
+                }
+                break;
 #endif
             // No valid multipress action
             default: