[ZHA] Uses for `exposes_features`

[TheJulianJES]

This issue collects the different use-cases for the exposes_features feature in ZHA (previously iteration was called quirk_id). This allows ZHA to change behavior depending on features set in quirks for devices.

For example, a device can expose an IAS_TAMPER feature and ZHA can then create the entity on its own, not requiring all v2 quirks to add a custom entity for this. There are also more sophisticated use-cases to only alter behavior or names of existing entities.

See below for a list where exposes_features could be used (and feel free to add any additional ones in the comments):

• Expose IAS tamper sensor for supported devices (ref PR: Add IASZone binary sensors for extra bits zha#246)
• Clean up (Frient) siren support to not show unsupported siren features and select entities (specific issue: [ZHA/Quirks] Allow duration only siren entities #61)
• 3-phase metering devices renaming first phase from (e.g.) "Current" to "Current A", in line with other "Current B" and "Current C" entities (ref comment)
  • We'll have to check if this is the correct solution for that problem. It would work to have an exposed feature for that in all quirks, but I wonder if we can just change the name for the first "A" phase attributes to include "A" if there's the respective "B" phase attribute present.
• There are more uses-cases, will expand list later...