Introduce proper wear-only mode for wearos4 and dexcom g6

[t0st]

Implements #3676:

• fix direct-connect from wearos4 to dexcom g6
• implement nightscout upload from wearos4 lte
• prevent data transfer to mobile if only_ever_use_wear is active

[thepartisan]

@t0st I am using this PR as basis for an attempt to add G7 support. Could you maybe quickly describe the pairing process for G6 for me here? After porting some more shortId-related things from app to wear I still struggle a bit here.

• As you are using the phone slot, will you pair G6 autonomously without prior phone pairing?
• Which name does G6 advertise?

[thepartisan]

@Navid200 , reaching out to you because I saw you commit quite a bit in the wear section...
Do you have any resource that describes how the pairing of app vs wear is supposed to work (design-wise)?
Do I pair the sensors completely new with wear app? I've started an attempt to integrate G7, but I am stuck at the initialization of pairing now and saw that for app there is "the plugin" feature. Do you know if this is this something I would need for G7 or should it theoretically also work based on the existing code?

Is there any interest/place for technical discussions?

[Navid200]

@thepartisan Please limit posts in a PR to what is specifically related to that particular PR.
For everything else, please use Discussions.

[t0st]

@thepartisan I wrote an answer in #3676