It didn't ever really make sense for it to be sharing the implementation
details of that (e.g. colouring of primary/dangerous actions), and with
the hotkey display things got outright hacky, so I'm decoupling it
entirely.
Bookmarks don't show on real beatmaps, but they do show in test scenes
(namely `TestSceneEditorSummaryTimeline`).
Also does some more changes to adjust the markers to the latest updates
to other markers.
This removes the BPM display, which is commonly cited to have
no functional purpose by users, and reduces the height of the bottom bar
in exchange for more space for the playfield.
Closes https://github.com/ppy/osu/issues/28750.
Yes this is not the perfect change to fix this (which would probably be
some framework change to take bounds of the parenting input manager into
account). I really do not want to go there and would like to just fix
this locally and move on. Due to the game-wide scaling container this
sorta works for any resolution anyhow.