Fixes #1021

Removing `react-select` and the new autocomplete. This experiment has
failed, so cleaning things up now.

Seems to build fine, will test later.

Depends on server change:
https://github.com/actualbudget/actual-server/pull/168

Enabling the new autocomplete for dev/preview deployments.

This will allow us to spot any more issues there might be before we
release the new autocomplete.

https://github.com/actualbudget/actual/issues/773

Refactored all feature flags to use the new `useFeatureFlag` hook.

Also added a new functionality to this feature flag: ability to define
custom "default" value for a feature flag. This will allow us to enable
the new autocomplete component for everyone using Netlify builds
eventually (need to address some issues before doing so).

Related to:
https://github.com/actualbudget/actual/issues/724#issuecomment-1455160250

Depends on https://github.com/actualbudget/docs/pull/126 to be merged
first.

Two changes here:
1. show "link account" only if actual-server is used (user is "online");
2. allow linking accounts only if Nordigen is configured (using new API
to get the status for it);

Also ported the `CreateAccount` modal to a functional component.

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used version is outdated by utilising GitHub tags to track the latest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

---------

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

Co-Authored-By: Matiss Janis Aboltins <886567+matissjanis@users.noreply.github.com>

* 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

Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>