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.
Touched on in https://github.com/ppy/osu/discussions/28581.
After a bit more usage of the editor I do agree with this and think that
making the fades a bit more gentle helps a lot.
Closes https://github.com/ppy/osu/issues/25426.
Different approach to prior ones, this just disables the relevant
actions when something related to save/export is going on. Still ends up
being convoluted because many things you wouldn't expect to touch save
do touch save, so it's not just a concern between export and save
specifically.
