This actually seems to be the case in catch (dash is bound to shift
twice). This is annoying but harmless, so let's work around it for now
to avoid ruining users' configs.
While this isn't strictly required (outside of rulesets, potentially),
I think it's best that we keep these counts in a sane state.
Right now, it will remove any excess. Arguably, in the case an entry is
found with too many, we should wipe all entries and re-populate the
defaults. Interested in opinions on that before merging. See
https://github.com/ppy/osu/discussions/15925 for an example where wiping
may be the more appropriate behaviour.
Changes all usages of `KeyCombination.ReadableString()` to
`ReadableKeyCombinationProvider.GetReadableString()`.
Subscribing to `KeymapChanged` is only required in `KeyButton`.
All other places query `GetReadableString()` every time.