Basic modal for switching extension settings (#907)

* Basic modal for switching extension settings

* Improve network usage by including field in query directly

Requesting individually is stupid, when it's a field that is already
available on the server

* Improve extension slider usability

- Always render the element, fixes animations
- Store the selected item in state, allows the back-button to re-open
  dialog

* Update src/modules/extension/components/ExtensionOptions.tsx

Co-authored-by: schroda <50052685+schroda@users.noreply.github.com>

* Update src/modules/extension/components/ExtensionOptions.tsx

Co-authored-by: schroda <50052685+schroda@users.noreply.github.com>

* Fix suggestions

* Use dialog instead of optionsPanel

* Extension options remove redundant NSFW info

* Apply suggestions from code review

Co-authored-by: schroda <50052685+schroda@users.noreply.github.com>

* Use proper dialog title and content for settings dialog

* Use `string | undefined` instead of `string | null` to satisfy `tsc`

---------

Co-authored-by: schroda <50052685+schroda@users.noreply.github.com>

src/lib/graphql/fragments/SourceFragments.ts

@@ -44,6 +44,7 @@ export const SOURCE_LIST_FIELDS = gql`
         lang
         iconUrl
         isNsfw
+        isConfigurable
         supportsLatest
 
         extension {