New team setup UI

[RobertJoonas]

Changes

This PR builds a new UI for the team setup page that is completely independent from TeamManagement code (which continues to work exactly the same way in team settings). The objective is to make the initial team setup UI cleaner in order to add team creation as an optional onboarding step.

The new UI is a simple form, where:

• name update happens only after hitting "Create team" (no db write on defocus anymore)
• the user can add multiple "email + role" rows before hitting submit
• the number of rows is limited by team_member_limit. Hitting the plus icon to add rows while at limit will not add any more rows and will display a "not-allowed" cursor
• invitations are sent only after hitting "Create team" (just like before, but there's no confusing extra "Invite" step anymore that might make it feel like the invitation was already sent)
• a validation error on any input field will flash an error message without resetting the form state itself (e.g. some email is invalid or the team name is reserved/prohibited)
• Any rows with an empty email are ignored

Note: The handrolled member-rows.js hook is quite a lot of code, but as a follow-up, I'm planning to introduce a Prima.Listbox component and use it here. So member-rows.js should eventually get rid of the hand-crafted keyboard navigation, focusing and blurring the dropdown, etc. We'll also be able to use Listbox in the TeamManagement LiveView to make the UX feel more snappy in high-latency scenarios.

Tests

• Automated tests have been added

Changelog

• This PR does not make a user-facing change

Documentation

• Docs have been updated

Dark mode

• The UI has been tested both in dark and light mode

[github-actions]

Preview environment👷🏼‍♀️🏗️
PR-6666