At first I was planning on making `CompareTo` implemented at
`IRulesetInfo` itself and shared across classes, but turns out it only
implements it explicitly and not allow direct `IRulesetInfo.Equals`
calls.
It messed with my head enough that I decided to just let each class have
its own implementation and only allow same type.
Came up when running the game after the recent breaking changes
(https://github.com/ppy/osu/pull/16722), where two template rulesets I
had loaded were erroring on startup but still being marked as available,
allowing them to crash the game on attempting to initiate relpay logic.
These cases are already handled for first-time ruleset loading via the
`GetTypes()` enumeration in `RulesetStore.addRuleset`, but when
consistency checking already present rulesets the only runtime
validation being done was `ruleset.CreateInstance()`, which does not
handle missing types or methods.