Add included services

[Symbitic]

This adds several characteristic capabilities that were missing.
It also adds included_services(), but it returns it as an array of UUIDs instead of objects.

[kdewald]

Hey @Symbitic, thanks a lot for these contributions!

In order to help me speed up the review, testing and merging of your features, could you split the changes of this MR into smaller MRs that I can individually try out?

Top of my mind, the separation I would make is:

• Characteristic capabilities
• Included services
• Power state

I hope this can help make the addition of features much faster and easier to test :D

[Symbitic]

Sure. I'll extract included services and power state from this and leave it as just capabilities.

[Symbitic]

I stand corrected: I leave this PR as included services and extracted capabilities and power state to separate PRs.

[Symbitic]

@kdewald any updates?

[CLAassistant]

All committers have signed the CLA.