Fix HomeKit with entity registry restoration where supported_features is a non-None falsey

[Jc2k]

Description:

Whilst trying to recreate #30638 i managed to write some unit tests that trigger the same exception. I don't think they are the root cause of that ticket but I thought it was weird that supported_features could be None - the restoration PR set it to 0 in a bunch of places. So this PR will propagate "falsies" that aren't None from the entity registry to the unavailable state. This fixes supported_features getting set as None instead of 0 (which is a valid value and should be allowed to be part of the state).

This includes a bunch of tests to make sure that HomeKit does handle states restored from the entity registry, including e.g. where no value for supported_features exists in the entity registry.

Related: #30638 #30094

CC @balloob

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the [development checklist][dev-checklist]

[balloob]

Good catch !