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

Closes #1069

I've not actually tested this change. Which is why I'm not changing it
to direct links (as they might not work).

Instead I'm just applying a very quick patch so the message would not be
misleading anymore.

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

Seems to build fine, will test later.

I noticed that the first run flow is suboptimal for people who want to
import an existing file from Actual/YNAB. I’ve moved the welcome modal
into the management app and set it up to appear when there are no
budgets available (which also has the benefit of allowing people to see
the modal again!)

I think there’s some weirdness around getting the modal to reappear when
deleting a budget file which I want to work out before merging this.

This PR also reorganizes the management app a bit to reduce usage of
modals (currently, hitting escape while the budget list is open leaves
you with a blank page).

<img width="539" alt="Screenshot_2023-03-18 08 53 54"
src="https://user-images.githubusercontent.com/25517624/226107462-b2b88791-1015-4397-b290-c64e7fcc0f41.png">

- [x] Ensure modal consistently appears when needed (no longer a modal!)
- [x] Fix e2e tests

*  (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