Clean up format of Skinning/Sounds and add Nightcore sample info

[CloneWith]

This might be part of the solution of #2589

Self-check

• The changes are tested against the contribution checklist

[Walavouchey]

• why are only some of these in tables? the ones which have additional information could have a "Notes" column for instance
• expand contractions ("aren't" --> "are not", etc.)
• "osu! client", "osu! cookie" instead of "osu!client" and "osu!cookie"
• the article should probably be renamed to something more grammatically correct than "Sounds skinning"

will check in more detail later

[CloneWith]

why are only some of these in tables?

Some of sounds are similar in filename and usage, then I tried to merge them into one line, for example the hitsound sets and the key-press-* set.

"osu! client", "osu! cookie" instead of "osu!client" and "osu!cookie"
the article should probably be renamed to something more grammatically correct than "Sounds skinning"

Just kept them without changes when rewriting, will change later.

the article should probably be renamed to something more grammatically correct than "Sounds skinning"

Skinnable sounds maybe I think?

[cl8n]

I have very far down a todo list that I wanted to write about these files:

nightcore-kick.wav
nightcore-hat.wav
nightcore-clap.wav
nightcore-finish.wav

idk if I'll ever get to it but maybe it's relevant to do in this PR.

[CloneWith]

Have read osu! lazer source code and tried on stable by myself. It's really odd that I didn't find nightcore-hat.wav being used in stable (not sure) but did in lazer, and the corresponding wiki page) seems unclear about this, not even mentioning it.

And found the sound playing mechanic of */3 or */6 times, can add it to this article (or Game modifier/Target Practice?)

[cl8n]

in stable

• the files are sourced from your skin, but not beatmap skin
• nightcore-hat plays only when slidertickrate is a multiple of 2
• nightcore-finish doesn't play if it's the first beat of a timing point that is omitting first barline
• non-4/4 works differently, to be hoenst it's so confusing and these skin elements are so niche that I wouldn't even bother documenting non-4/4

otherwise it works same as lazer

[cl8n]

rest of the changes seem fine, there's still a lot to improve about this article but the new layout here is certainly better

just fix NC and that's good for this PR