Part 4 of the migration. Final moves.

Previous PR: https://github.com/actualbudget/actual/pull/1420

Part 3 of the migration.

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

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

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

Extracted from #984

Introduces a **ResponsiveProvider** as the sole location that tracks
window size and makes that info available to the entire app. This can be
used for media queries and size-based component switching.
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Co-authored-by: Jed Fox <git@jedfox.com>

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)

This implements a simple indicator showing the user if the currently
used version is outdated by utilising GitHub tags to track the latest
version.
Closes #463

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

* Allow the server to auto-configure the server URL for the client

* Extract server URL/version logic out to ensure consistent updates

* ()

* Be more explicit about when the server version is re-fetched

* Use a single layer of context provider

* Move the bootstrap route to /account/needs-bootstrap

* No more `isActual`

* Refactor to call subscribe-needs-bootstrap instead of fetch()

* Dedupe calls to subscribe-needs-bootstrap

* Don’t revalidate the server when we just validated it

* simplify

* Fix setServerURL

*  (prettier) adding trailing commas

* More commas

*   upgrade eslint-plugin-import and fix issues

* Change import ordering

* Make ButtonSetting more generic

* Add an “Experimental Features” section in the settings

* Fix text color

* Put experimental features behind another link

* Update Encryption.js

* Update FixSplits.js

* Remove unused variable

* That’s what I get for coding on my phone

Co-authored-by: Matiss Janis Aboltins <matiss@mja.lv>

* Center the settings UI when the sidebar is collapsed

* Fix lint

* 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>