app e2e tests

[illume]

We need to have some e2e tests for our app.

• Running the e2e tests is more important now that our production builds are more different than our development builds.
• Note: This is different from another issue we have about running the apps( Add test for running the app #2166 ). Running the apps also has value, because it tests our packaging as well.
• This one should work with the production build, and not the development server. Because we want to test the production build.
• This provides something our existing e2e tests doesn't. There is code in Headlamp that only runs for the app, and not in the in-cluster version.

Electron has a page in their documentation with some options: https://www.electronjs.org/docs/latest/tutorial/automated-testing#using-playwright

[illume]

There were PRs here:

• WIP: fixes for app e2e #2194
• Initial Playwright E2E Test for App Mode in Electron #2344

What the acceptance criteria should be for a first PR:

• get a first minimal PR merged, not to do the whole task
• at least one app test is run (least complicated thing that works)
• if it's just a test that runs locally, that is fine for a first PR
• use small atomic commits to make sure CI does not break

[vyncent-t]

Planning on reverting back to the local first prio for playwright app mode testing, this work will come from #2344 and be pushed into this branch

• move working app mode playwright test into the app folders

We will be closing issues:
#2332 (no longer running tests from one location)

from sync w/ @illume