The old design was apparently somehow tolerant of multiple instances of
the same mod in `SelectedMods`, but the new one is not.
Fix the test, because appending to a list of mods that was getting
modified by previous tests is generally not how tests should be
written.
Provides initial implementation of new chat overlay in component
`ChatOverlayV2`. Contains only the basic functionality required for
a functioning chat overlay according to the new design with the intent
of added the rest of the functionality in subsequent PRs.
Backports existing tests for the current chat overlay except for ones
testing keyboard shortcuts (since they haven't been added) and tab
closing behaviour (since no tabs).