Split PropertyInfo and MethodInfo off from Object into their own separate files.

[nlupugla]

To avoid cyclic dependencies in a different PR I am working on (#82198), I need to be able to include PropertyInfo and MethodInfo without also including Object. Additionally, separating out these structs helps keep Object.h/cpp focused on just Object stuff.

[nlupugla]

Hmm, I'm noticing that the Linux build is failing because Connection already seems to be defined in some third-party file. Should I put connection.h/cpp in maybe namespace Signal to avoid the conflict? Alternatively, I could move Connection to be inside Callable. The only other option I can think of really is to rename Connection to something like SignalConnection.

[nlupugla]

I actually managed to find a different solution so that structs can work without relying on splitting PropertyInfo, MethodInfo, and Connection into separate files. I think splitting off PropertyInfo and MethodInfo into their own files is still good for code hygiene, but I'll leave Connection attached to Object to avoid the namespace conflicts over Connection.

If others don't like the change of splitting of PropertyInfo and MethodInfo, I'm fine with closing this PR.

[nlupugla]

I've resolved the conflicts on this branch and left the Connection struct as part of Object.

[Geometror]

Sorry for the long wait. For me this is sensible, but someone from core should take a look at this as well.
Should be safe to merge, as I just checked that there were no changes of MethodInfo/PropertyInfo within the last few months.

[akien-mga]

Makes sense to me conceptually. Could use a rebase to make sure it still works.