Big Trait Changes

[TTWNO]

Summary

Split BusProperties into the const &'static strs (still called BusProperties), and message conversion: MessageConversion (TODO: name).

All trivial events (where they contain only the field item) now implement From<ObjectRef>.

All events that implement From<ObjectRef> get their MessageConversion implementation for free (blanket impl).

Rename:

• from_message_parts(ObjectRef, Self::Body), to
• try_from_message_unchecked(&zbus::Message)

An additional check was added to all implementations of From<&zbus::Message> (the macro) requireing that the body signature match the event's body signature—this supplements the xisitng checks on the interface and member.

Commits

• Split BusProperties into two traits
• use new trait in sending event code
• Feature gate new MessageConversion trait behind 'zbus'
• Take zbus::Body instead of Self::Body in from_message_unchecked
• from_message_parts_unchecked -> try_from_message_unchecked
• Pass &Message to new try_from_message_unchecked
• Add macro to implement From
• Fix missing doc link
• Auto-implement MessageConversion for trivial case.
• Remove now unused From for EventBodyOwned
• Use full message to check tests
• Make sure to check signature validity before calling try_from_message_unchecked

TODO

• [x] Ensure Event and interface-grouped enums use _unchecked instead of TryFrom<&Message>
• [x] Add _unchecked variant deserialization for interface-grouped enums, which will not check the validity of the interface before continuing,

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 94.87603% with 31 lines in your changes missing coverage. Please review.

Project coverage is 84.67%. Comparing base (bfa3bc4) to head (cb70e23).

Files	Patch %	Lines
atspi-common/src/events/cache.rs	84.54%	17 Missing :warning:
atspi-common/src/events/mod.rs	91.97%	11 Missing :warning:
atspi-common/src/error.rs	0.00%	2 Missing :warning:
atspi-connection/src/lib.rs	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #206 +/- ## ========================================== - Coverage 87.23% 84.67% -2.56% ========================================== Files 42 43 +1 Lines 3595 3223 -372 ========================================== - Hits 3136 2729 -407 - Misses 459 494 +35 ```

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[TTWNO]

Shout out to our extensive tests that caught a ton of the mistakes I was making along the way! I would have forgot to add the signature check if we didn't have a test specifically that matched the interface+member but gave a blank body.

[TTWNO]

Rebased on main.