This cleans up all of the usage of `<a>` in the codebase. Now all
external links get the appropriate attributes added.

Co-authored-by: Jed Fox <git@jedfox.com>

Depends on https://github.com/actualbudget/docs/pull/202.

Closes #944, closes #532. ~WIP because something is causing the test
budget to fail to create because it’s using INSERT instead of UPDATE sql
queries. (Or not? I have no idea)~

Seems to build fine, will test later.

*  (prettier) adding trailing commas

* More commas

* style: enforce sorting of imports

* style: alphabetize imports

* style: merge duplicated imports

* style: enforce ordering of imports

* style: sort imports in loot-core

* style: sort imports in desktop-client

* style: sort imports in loot-design

* style: manual fixes