Remove reset() function

Version 3.0 would move away from ever manually stopping the music service on Android, to make it more akin to how popular music/podcast apps work. destroy() has already been removed, and the same should be done for reset(). Currently, at least for Android, the reset function doesn't actually reset anything:

    @ReactMethod
    fun reset(callback: Promise) = scope.launch {
        if (verifyServiceBoundOrReject(callback)) return@launch

        musicService.stopPlayer()
        callback.resolve(null)
    }

iOS side should also be handled.

I think this was put together before we finalised 3.0. This issue is probably obsolete in favor of proposals for 4.0.