Always show "sort" dropdown but disable in cases it doesn't (yet) work

[peppy]

Avoids UI components shifting around, breaking muscle memory.

• Addresses Change new sort dropdown menu in song select placement #34443.
• Closes "step" when hiding Sort dropdown on SSV2 #34415.
• Supersedes and closes Swap leaderboard scope and sort dropdowns #34446.

[bdach]

unsure how to feel about the sort mode dropdown remaining at the last value chosen before it was disabled when switching to a leaderboard scope that does not support sorting

is kind of ambiguous as to whether the resulting scores should be sorted by date or not

[bdach]

other than the above fine I guess

[peppy]

Good observation. I've fixed this, and also made sure we're properly binding to the configuration value, in case it's altered elsewhere in the game at a later point.