Added "LN Ratio" display in Mania in the place of useless "key count"

[pacowoc]

The "Key Count" metric in mania is very useless since you are already expected to play maps with a specific Key Count when you are queueing.
This PR inserts the proportion of LNs (Long Notes) in the place of that metric since it is one of the ways players can gudge their skillsets (This idea comes from reddit)
Also improved the test suite for other skillsets by making the architecture more minor ruleset friendly

Addresses #37568.

[IceDynamix]

i think this should be solved by changing the implementation of ManiaRuleset.GetBeatmapAttributesForDisplay instead? this feels very hacky. there is also no consideration for localization because the attribute labels currently use SongSelectStrings. also, the number should also be formatted as a percentage if anything.

[pacowoc]

i think this should be solved by changing the implementation of ManiaRuleset.GetBeatmapAttributesForDisplay instead? this feels very hacky. there is also no consideration for localization because the attribute labels currently use SongSelectStrings. also, the number should also be formatted as a percentage if anything.

There are absolutely zero consideration of localization in 99% of ranked UI anyways

[pacowoc]

Also the Tests here are bugging so much that it is insane, the pickscreen test stop midway on first run but runs normally on second run lmao, idk why

[pacowoc]

i think this should be solved by changing the implementation of ManiaRuleset.GetBeatmapAttributesForDisplay instead? this feels very hacky. there is also no consideration for localization because the attribute labels currently use SongSelectStrings. also, the number should also be formatted as a percentage if anything.

Re-implemented with your suggestion

[smoogipoo]

LGTM. Not 10000% sure about the extra Ruleset method but it's probably the easiest place to do it for now.