Repeater and other power optimizations (#2999)

* End wire if we find no i2c devices

* Set tx-power to 0 on nrf bluetooth shutdown

* Change polling interval of PowerFSM to 100ms instead of 10ms

* Guard 3v3

src/platform/nrf52/NRF52Bluetooth.cpp

@@ -211,6 +211,7 @@ void NRF52Bluetooth::shutdown()
     // Shutdown bluetooth for minimum power draw
     LOG_INFO("Disable NRF52 bluetooth\n");
     Bluefruit.Advertising.stop();
+    Bluefruit.setTxPower(0); // Minimum power
 }
 
 bool NRF52Bluetooth::isConnected()
@@ -333,4 +334,4 @@ void NRF52Bluetooth::onPairingCompleted(uint16_t conn_handle, uint8_t auth_statu
         LOG_INFO("BLE pairing failed\n");
 
     screen->stopBluetoothPinScreen();
-}
+}