Make pebble integration optional

[Enovale]

Add a setting in the voice prompts settings tab to disable the Pebble Voice notification added in 3f9a611

This hopes to resolve #4686 where the "integration" Voice notification shows less information and is generally less helpful than the normal notification, but that notification cannot be disabled normally.

I wonder why this integration exists at all, but in good faith I just want it to be optional. If someone knows a good use case for it please let me know as I'm curious.

[vshcherb]

This might be too old and we need to disable pebble completely better

[sonora]

@vshcherb Yes, time to deprecate our Pebble alerts, I would say.

[Enovale]

Integrating an actual navigation app for pebble could be interesting but that's probably out of the scope of osmand? An example of this would be Nav Me, in fact the existing Nav Me app could probably be interfaced with and told nav data except using OsmAnd data instead