Add react-based frontend

[trungleduc]

Code changes

• Remove old jinja-based UI
• Add new UI based on React
• Update CI, add isolated and UI tests, close End to end tests with Playwright #68

Screenshot

• Environment list

• Environment dialog

• Server list

• Server dialog

• Machine profiles

[jtpio]

Thanks @trungleduc for working on this!

Do you have a screenshot around for what the new frontend / UI looks like, even if it's still a draft for now and subject to changes? Thanks!

[trungleduc]

@jtpio I updated the first post.

[trungleduc]

@jtpio this PR is ready again

[jtpio]

If this simplifies the setup, we could also use npm instead of yarn?

[trungleduc]

indeed, updated!

[jtpio]

Maybe this shell (and the others below) could be removed if we use the base-setup action?

[jtpio]

Thanks @trungleduc!

It's also really nice to have UI tests and reference snapshots 👍
Maybe we could even replace the screenshots in the README by the snapshots from the UI test, so the README stays up-to-date when new changes land?

[jtpio]

I didn't go through the whole frontend code in the details, but overall it looked good. We can always iterate on it later if something needs to be fixed.

[trungleduc]

Thanks @trungleduc!

It's also really nice to have UI tests and reference snapshots 👍 Maybe we could even replace the screenshots in the README by the snapshots from the UI test, so the README stays up-to-date when new changes land?

I will do it in the follow-up PR