[PUI] Plugin settings UI (#8228)

* Visual tweaks for admin pages

* Provide admin js file via API

* Backend fixes

* Tweak error detail drawer

* Refactor plugin detail panel

- Split out into separate files
- Use <Accordion />
- Display custom configuration (if available)

* Refactoring

* Add custom configuration to sample UI plugin

* Bump API version

* Add separate API endpoint for admin integration details

* Refactor plugin drawer

* Null check

* Add playwright tests for custom admin integration

* Enable plugin panels in "settings" pages

* Fix for unit test

* Hide "Plugin Settings" for plugin without "settings" mixin

* Fixes for playwright tests

* Update playwright tests

* Improved error message

src/frontend/tests/baseFixtures.ts

@@ -67,6 +67,8 @@ export const test = baseTest.extend({
           ) < 0 &&
         msg.text() !=
           'Failed to load resource: the server responded with a status of 400 (Bad Request)' &&
+        !msg.text().includes('http://localhost:8000/this/does/not/exist.js') &&
+        url != 'http://localhost:8000/this/does/not/exist.js' &&
         url != 'http://localhost:8000/api/user/me/' &&
         url != 'http://localhost:8000/api/user/token/' &&
         url != 'http://localhost:8000/api/barcode/' &&