Apparently useful in modding workflows when you want to test out a few
different variants of a thing.
Re-uses `Ctrl-L` binding from stable. Some folks may argue that the
dialog makes the hotkey pointless, but I really do want to protect
users from accidental data loss, and also if you want to power through
it quickly, you can hit the 1 key when the dialog shows, which will
bypass the hold-to-activate period (which wasn't intentional, but so
many people want a bypass at this point that we're probably keeping that
behaviour for power users).
* Calculate hit windows in performance calculator instead of databased difficulty attributes
* Apply mods to beatmap difficulty in osu! performance calculator
* Remove `GreatHitWindow` difficulty attribute for osu!mania
* Remove use of approach rate and overall difficulty attributes for osu!
* Remove use of hit window difficulty attributes in osu!taiko
* Remove use of approach rate attribute in osu!catch
* Remove unused attribute IDs
* Code quality
* Fix `computeDeviationUpperBound` being called before `greatHitWindow` is set
- Caches `DrawableRuleset` in editor compose screen for mania playfield adjustment container (because it's used to wrap the blueprint container as well)
- Fixes `ManiaModWithPlayfieldCover` performing a no-longer-correct direct cast with a naive-but-working approach.
In particular, mania-specific beatmaps that normally go via the
"passthrough" generator should not adjust the stored pattern value.
The "spinner" generator, which was previously intended to be used for
non-mania-specific beatmaps, is now valid even for mania-specific
beatmaps, and uses this value.
In other words, another way of writing this would be:
```csharp
if (conversion is SpinnerPatternGenerator || conversion is
PassThroughPatternGenerator) ? lastPattern : newPattern;
```
Better symbolises the intent of this generator which is to convert
hitobjects in their most simple forms - anything with an end time
converts to a hold or otherwise converts to a normal note.
A big part of these changes is refactoring, which is somewhat necessary
because it was previously implemented as two separate pathways which
in-fact need to be joined at the hip when handling spinners.
I've chosen to use `IHasLegacyHitObjectType` here because there's no
other flag that allows us to tell `ConvertHold` apart from
`ConvertSpinner`.
