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).
This was reported in https://github.com/ppy/osu/pull/28474, albeit the
code changes proposed there did not fix the issue at all.
See 8b6385f7d0e9ac575b1895b8118aeeeac13d6026 for demonstration of the
crash scenario. Basically what is happening there is:
- The starting premise is that there is a spinner placement active.
- At this time, a drag selection is started via the timeline.
- Once the drag selection finds at least one suitable object to select,
it mutates `SelectedItems`.
- When selection changes for any reason, the `HitObjectComposer`
decides to switch to the "select" tool, regardless of why
the selection changed.
- Changing the active tool causes the current placement - if any -
to be committed, which mutates the beatmap.
- Back at the drag box selection code, this causes a "collection
modified when enumerating" exception.
The proposed fix here is to eagerly commit active placement - if any -
when drag selection is initiated via the timeline, which avoids this
issue. This also appears to vaguely match stable behaviour and is sort
of consistent with the logic of committing any outstanding changes upon
switching to the selection tool.
Makes it hard to test anything because `EditorBeatmap`'s `Update` method
updates whether a beatmap has timing or not (enabling the placement
controls).
Also adds a basic timing point to allow for better testing.
