Web: monitor API improvements

[daxpedda]

• Improved the documentation to point users into the right direction from all kinds of methods and types.
• De-duplicated some code and added more comments.
• Implement an ID system to correctly and efficiently implement Eq, Hash, Ord, PartialEq and PartialOrd.
• Fixed screen locking support being cached thread local, ergo calling from a different thread would require to make the check again, not fulfilling its purpose as a fast-path at all.

Follow-up to #3801.

[daxpedda]

I did some thinking about the API complexity of this implementation.
There are basically two different MonitorHandle types, but they are the same Rust type. Users can query which type it is with is_detailed(), but that's all not exactly ideal.

I think what could be done about that in the future is to split up the orientation and screen locking stuff away from MonitorHandle entirely, that way there won't be a use for MonitorHandle on Web at all unless its the "detailed" type.
However, this requires a new API surface that we have yet to think about and implement, which requires some cross-platform coordination as well.

In any case, its some food for thought.