Until now, the implementation of the overrides in `SelectionBlueprint`
have been confusing to the point where I would just implement by
trial-and-error (or copying from an existing implementation). This was
due to a combination of using "object" space coordinates
(ie. the thing the `Blueprint` is operating on) and screen-space coordinates.
This change switches all event related coordinates to screen-space,
which is how we already handle rotation/scale operations. With the
introduction of other editor types where the related objects are
drawables, this also makes a lot more sense.
Further separates them from `IBeatSnapProvider`'s `SnapTime`, and groups them together more, to prevent confusion between the two interfaces.
Also changes the xmldoc of the reference time to that of `IBeatSnapProvider` for consistency.
Seems `EditorBeatmap` already implements a different kind of `SnapTime` from `IBeatSnapProvider`, so method names here aren't great.
This is very similar to what https://github.com/ppy/osu/pull/12558 is doing, so may need to do some duplicate resolution later, especially surrounding `ClosestBeatSnapDivisor`.
Worth noting that this change makes 1/7, 1/5, etc unsupported for now, as we now rely on `BindableBeatDivisor.VALID_DIVISORS`.
Uses the resolved working beatmap instead of resolving it every time.
Also uses the EditorBeatmap itself as playable beatmap, as it is of type `IBeatmap` already, and `.PlayableBeatmap` forwards everything anyway.
This is different from the working beatmap's `.Beatmap` property in that it is mutated by the ruleset/editor.
So hit objects, for example, are actually of type `Slider` and such instead of the legacy `ConvertSlider`.
This should be preferred over `workingBeatmap.Beatmap`.
