Fixes#22306.
Changes beatmap saving so that by default it does not transfer
the hashes in collections, and only transfers them when saving the same
difficulty in the editor.
Issue seems to have been introduced in https://github.com/ppy/osu/pull/20641.
This regressed with https://github.com/ppy/osu/pull/20850 because the
function was used in other places which expect it to factor slider
velocity into the equation.
Rather than reverting, I've added a new argument, as based on the method
naming alone it was hard to discern whether SV should actually be
considered.
The reason for the change in #20850 was to avoid the SV coming in from a
reference object which may not have a correct SV in the first place. In
such cases, passing `false` to the function will give the expected
behaviour.
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.