Djblets received support for type hints for TypedProperty. While

verbose, this allows us to ensure that the right values are going into

and coming out of these properties.
This updates all usage to incorporate typing, and adds typing

information for a few additional fields in some of the affected classes.
An argument could be made for switching away from TypedProperty in

time. However, it's still useful for ensuring strict types in key areas

like diff parsing and SCM results.

Unit tests pass.
Checked that pyright and mypy were happy.