Fix handling of combo and combo colours around spinners

[smoogipoo]

Fixes #24270

Lessons learnt (from osu!stable):

During decode:
- Spinners get a NewCombo value from the decoded hitobject line.
- Spinners cannot have a ComboOffset, even though parts of code are written as if they could.
- The first hitobject following a spinner has NewCombo = true.
- The first hitobject in the beatmap has NewCombo = true.

During post-processing (after decoding):
- The first hitobject after each break gets NewCombo = true.
- For combo colour, spinners never start a new combo.
- For combo text, only the first hitobject after a spinner starts a new combo.

[bdach]

Tests are a bit red :(

[smoogipoo]

Looks like that was yet another incorrect implementation/assumption in lazer. Tested the beatmap file against stable and updated accordingly.

[peppy]

I haven't checked the underlying osu!stable assumptions (have faith that you got these right as per conversations yesterday).

Code here looks good / better than what we had.