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.
Also didn't notice a particular case here, but if all code passes up
until we get to the `foreach (var h in nestedHitObjects)` below, then we
could end up stuck here for quite a while.
The subscription in which the guards were present was moved from
constructor to `ApplyDefaults()`, and at that point neither the sample
control point or the difficulty point can be the default point, because
there are explicit paths that overwrite those with blank points in the
same methods, prior to the subscription's registration.
The only worry would be that someone would set the default point on the
object themselves, but at that point that is most likely programmer
error anyhow.
In editor contexts, the `StartTimeBindable` subscription in `HitObject`
was firing before defaults were applied, which in the case of sliders
manifested in an infinite end time. `ApplyDefaults()` also did not
always set the time of the control point to the correct value, which
matters when the beatmap is encoded.
Ensure that the control points receive the correct time values during
default application, and only register the `StartTimeBindable` change
callback after defaults have been successfully applied.