Follow-up to https://discord.com/channels/188630481301012481/188630652340404224/1364909125812617258. Not sure if better, but an attempt was made?
Closes https://github.com/ppy/osu/issues/31615.
As proposed in https://discord.com/channels/188630481301012481/188630652340404224/1327309179911929936.
Closes https://github.com/ppy/osu/issues/25608. Logic mostly matching stable. All operations are done on `ComboOffset` which still makes overridden combo colours weirdly relatively dependent on each other rather than them be an "absolute" choice, but alas... As per stable, two consecutive new combos can use the same colour only if they are separated by a break: https://github.com/peppy/osu-stable-reference/blob/52f3f75ed7efd7b9eb56e1e45c95bb91504337be/osu!/GameModes/Edit/Modes/EditorModeCompose.cs#L4564-L4571 This control is only available once the user has changed the combo colours from defaults; additionally, only a single new combo object must be selected for the colour selector to show up.