This is a "two-birds-with-one-stone" change, which addresses both
https://github.com/ppy/osu/issues/28744 and
https://github.com/ppy/osu/issues/11311 simultaneously.
- The replay stability issue caused by time instants being rounded to
nearest integer is fixed by this, because flooring and
subtracting/adding 0.5 from the hit window threshold makes it
impossible for a judgement to switch to anything else after replay
rounding is applied - all hit windows are always a full integer plus
0.5 milliseconds, which immunizes them to rounding-to-full-ms issues.
- The direction of applying the 0.5 adjustment additionally fixes the
disparity with stable - in osu! and taiko 0.5 is subtracted as
hit window ranges in those rulesets are exclusive on stable, while in
mania 0.5 is added, as the hit window ranges there are *inclusive* on
stable.
As should be obvious, this materially changes hit windows. To what degree
this is a *significant* change is up for discussion; I would say "no"
since hitting half a millisecond changes would require 2000fps input
recording, and we're still timestamping inputs using the update thread's
clock, that gives a 1ms resolution at best.
In the worst case, in osu! and taiko, this can change a hit window range
by 1.5ms (e.g. 300.9ms -> floored to 300ms -> 299.5ms after subtraction
of the half). It's more than the best-case resolution of input
timestamps, but not by much. Considering how cleanly this resolves the
issues in question, I see it as an acceptable tradeoff.
This change pulls back a significant degree of overspecialisation and
rigidity in the class structure of `HitWindows` to make subsequent
changes to hit windows, whose purpose is to improve replay playback
accuracy, possible to do cleanly.
Notably:
- `HitWindows` is full abstract now. In a few use cases, and as a
reference for ruleset implementors, `DefaultHitWindows` is provided as
a separate class instead.
This fixes the weirdness wherein `HitWindows` always declared 6 fields
for result types but some of them would never be set to a non-zero
value or read.
- `HitWindow.GetRanges()` is deleted because it is overspecialised and
prevents being able to adjust hitwindows by ±0.5ms cleanly which will
be required later.
The fallout of this is that the assertion that used `GetRanges()` in
the `HitWindows` ctor must use something else now, and the closest
thing to it was `GetAllAvailableWindows()`, which didn't return
the miss window - so I made it return the miss window and fixed the
one consumer that didn't want it (bar hit error meter) to skip it.
- Diff also contains some clean-up around `DifficultyRange` to unify
handling of it.