BBcode [right] align

[someonecantcode]

supersedes #12431
resolves #12356

in #12431, kama talks about rewriting the <center> implementation since it is deprecated but i don't know if i should do something about it. Quick question, if this gets merged, should i update the documentation in https://github.com/ppy/osu-wiki/blob/master/wiki/BBCode/en.md ?

Tested for main audio, spoilerboxes, videos results:

[peppy]

Also seen in #12431.

[LiquidPL]

the box/spoilerbox header can get left aligned when open

[LiquidPL]

this should probably reference .bbcode-spoilerbox instead.

[someonecantcode]

the box/spoilerbox header can get left aligned when open

hello im not sure what you meant by "header can get left aligned when open"? I wasn't able to recreate what you said.

[right][box=NAME]
text
[/box][/right]

[right][spoilerbox]text[/spoilerbox][/right]



[spoilerbox]text[/spoilerbox]

[spoilerbox][right]text[/right][/spoilerbox]

Anyways, yeah thanks for the catch on the .js-spoilerbox; I changed it to .bbcode-spoilerbox instead and works the same. I will rebase and squash in a moment.