Move timeline toggle controls to "view" menu

[bdach]

RFC

• Waveform toggle off replaced by 0% opacity
• Rest migrated to the submenu depicted above
• As a bonus, this will now be persistent across sessions by the virtue of being stored to OsuSetting / ini config

Based on this bit of reddit feedback:

I don't get why the options on the left of the timeline (waveform, ticks and bpm) are permanently there, and not in a drop-down menu in the View section? Who wants to see less of the timeline?

that I tend to agree with.

This also changes some paddings because stuff looked kind of bad after just moving the settings. There's still some badness elsewhere on the timeline (colour clashes / alignment mostly) but I kinda don't care and want to put functionality above appearance for the time being. Can be adjusted upon feedback if this isn't rejected outright.

master	b42752c9f06d10da5985ff4ab10e8e728a1a5be0	03049d45bb136826c70d632825150492ba36cbc1

editor playfield scale	gameplay playfield scale

[peppy]

The paddings feel a bit tight (especially with timing changes hidden), but I think this is what people are asking for, so let's go with it.