Small speed up to fetch characteristic values

[bdraco]

We can avoid most of the body of this function for the common case. We call this a lot when adding entities

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5d8c8f1) 74.47% compared to head (74b0822) 74.51%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #363      +/-   ##
==========================================
+ Coverage   74.47%   74.51%   +0.04%     
==========================================
  Files          99       99              
  Lines        9331     9332       +1     
==========================================
+ Hits         6949     6954       +5     
+ Misses       2382     2378       -4     

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[Jc2k]

Tangentially related, but do you think there is a nicer way to replace this entirely so we can do more strict type checking in HA? Was thinking about read_int(), read_string(), etc. I guess they could return self._value pretty directly and avoid the body too. But not sure about returning enums of different types and different TLV structs with that approach. Can sort of imagine a read_struct that took a class, and the return value was generic over that parameter.

If we did that is there a performant way (or, do we disable asserts at runtime in HA?) to check self.format matches the read function getting called?

[bdraco]

I think we could subclass char objects for each HAP type with the value param typed to the expected return. Than each CharacteristicTLV8, etc could implement its own value function or use the default.