The previous implementation of `SampleInfo`'s equality members was not
completely correct in its treatment of the `sampleNames` array. While
`Equals()` compared the values of `sampleNames` using `SequenceEqual()`,
therefore performing a structural check that inspects the contents of
both arrays, `GetHashCode()` used `HashCode.Combine()` directly on the
arrays, therefore operating on reference equality. This could cause the
pooling mechanism of samples to fail, as pointed out in #11079.
To resolve, change the `GetHashCode()` implementation such that it also
considers the contents of the array rather than just the reference to
the array itself. This is achieved by leveraging
`StructuralEqualityComparer`.
Additionally, as a bonus, an array sort was added to the constructor of
`SampleInfo`. This is intended to be a "canonicalisation" processing
step for the array of sample names. Thanks to that sort, two instances
of `SampleInfo` that have the same sample names but permutated will also
turn out to be equal and have the same hash codes, given the
implementation of both equality members. This gives `SampleInfo`
set-like semantics.
Regressed in #10696. The old `IsFirstHideableObject()` method did not
consider nested hitobjects, while its replacement -
`IsFirstAdjustableObject()` - did. Therefore, spinner ticks could be
considered first adjustable objects, breaking the old logic.
There is no need to match over `SpinnerBonusTick`, as it inherits from
`SpinnerTick`.
`GameplayBeatmap` has to be used instead of the normal bindable
`Beatmap`, beecause the former uses osu!-specific hitobjects, while
the latter returns convert objects (i.e. `ConvertSlider`s).
Similarly, the mod has to be fetched from the player instead of the
global bindable, as `Player` has its own cloned instance of the mod, to
which the beatmap is applied. The global bindable instance does not have
`FirstObject` set.
