some minor cleanups

* Suppress warnings about conflicting library names in platformio.ini by
  explicitly picking the libraries by id that we want.
* fix unused static function warning by making it not static ;)
* declare arduino-fsm as dependency for BluetoothOTA. Hopefully this
  fixes the CI builds?

Tested: `pio run` builds.

lib/BluetoothOTA/library.json

@@ -21,6 +21,10 @@
   "platforms": "*",
   "dependencies": [
     { "name": "Update" },
-    { "name": "ESP32 BLE Arduino" }
+    { "name": "ESP32 BLE Arduino" },
+    {
+      "name": "arduino-fsm",
+      "version": "https://github.com/geeksville/arduino-fsm.git"
+    }
   ]
 }