feature(argus): Release Planner

[k0machi]

This PR adds a new way to manage releases inside Argus, called Release Planner. Release Planner replaces current Release Scheduling mechanism (but not the Duty Calendar for now). Main features include:

• Plans are now separate entities (replacing one global release schedule)
• Each plan contains tests, groups and people it will be using for assignments
• Plans can target a specific scylla version to scope the plan to a point or RC release.
• Plans can be edited, deleted and copied.
• On copy, plan will offer to replace missing tests/groups if it is being copied to another release and that release is missing required tests.
• Each plan automatically creates and maintains a view dashboard for said plan and can be viewed from plan overview page or inside views overview
• The new assignment logic is now applied to all releases not marked as "endless" (perpetual in the admin panel). Currently the only one that is marked that way is scylla-master.

Task: https://github.com/scylladb/argus/issues/377 Task: https://github.com/scylladb/qa-tasks/issues/1717

[k0machi]

Demo:

https://github.com/user-attachments/assets/c9e47bd5-992a-4dab-ad94-407591ad12dd

[k0machi]

@roydahan @fruch Ready for review

[roydahan]

Do you want to record a demo?

[k0machi]

Do you want to record a demo?

There's a slightly outdated one a message before mine, but I can record an up-to-date one soon.

[k0machi]

@roydahan new demo for the full functionality with explanations:

https://github.com/user-attachments/assets/632bcd89-4d6c-4bd4-8644-a019139ac79c

[roydahan]

Looks good. There could be some improvements but I think we can start with it and improve it as we go.

[k0machi]

Looks good. There could be some improvements but I think we can start with it and improve it as we go.

One more thing - for a plan that has tests already selected (in edit or create exec plan mode), should opening Grid View clear that list? Currently it will merge the selection and I think that might be annoying to use.