Add support for classes in Python doc pages

[Wumpf]

e.g. LogHandler and LogLevel aren't in the generated documentation page yet because of this

[jleibs]

The doc pages should support classes already. You should be able to add "log.text.LoggingHandler" to the generator.

The class annotations seem to be working in the package manifest: https://rerun-io.github.io/rerun/docs/python/latest/package/rerun/log/text/#rerun.log.text.LogLevel

[emilk]

For instance: We don't have a link to AnnotationContext from https://ref.rerun.io/docs/python/v0.6.0/common/

[nikolausWest]

Done in #2401