fix: Fixed library warnings

[Kinchul]

Title: Fixed library warnings

Summary

This fixes compiler warnings in the library after the recent D-Bus dependency update (and some legacy warnings). It does not change the code behavior, just makes it compilation cleaner.

What changed

• disabled nullable analysis in the generated D-Bus bindings since the generator does not emit nullable annotations
• removed the duplicated local CloseSafeHandle shim now that Tmds.DBus already provides that type
• fixed nullable/lifecycle issues in the handwritten library wrappers
• kept backward-compatible population of legacy DeviceProperties members while suppressing the obsolete-member usage locally

Disclosure

This was done with the help of AI.

[Kinchul]

FYI I rebased my changes on the most recent commit on the develop branch to ease any upcoming merge. I removed WaitForPropertyValueAsync from DeviceExtensions since it's now implemented in a more general way in WatchableExtensions.