Part 3 of the migration.

Part 2 here: https://github.com/actualbudget/actual/pull/1419

Seems to build fine, will test later.

This PR improves the consistency of the settings UI by moving everything
(except the budget name field on mobile) into `<Setting>` boxes.
Additionally, it adds a “Settings” option to the file dropdown menu (I
keep expecting it to be there, and I think it’s reasonable to expose it
in both locations so it’s easier to access)

*  (prettier) adding trailing commas

* More commas

* Split the Settings component into multiple files (#434)
* Remove need for isMobile in CSS: lean on media queries in styles.js and glamor

Co-authored-by: Matiss Janis Aboltins <matiss@mja.lv>
Co-authored-by: Jed Fox <git@jedfox.com>