feat(nimbus): Approval and rejection flow

[yashikakhurana]

Because

• We want to add approval and rejection flow on the new summary page

This commit

• Add option to approve and Launch
• Add the option to reject the experiment with the message
• Shows the timeout message

Fixes #12072
Note: This currently does not show the rejection reason-which I will add in the separate PR

Approval flow

Untitled.mov

Rejection flow

Screen.Recording.2025-01-22.at.3.38.00.PM.mov

Timeout message

[yashikakhurana]

Blocked on #11932

[jaredlockhart]

Okay! This is already looking great 🎉 🎉 🎉

Couple things I notice from local testing:

• doesn't display rejection note
• doesn't immediately call remote settings sync

Look at what the V5 serializer does here on save:

https://github.com/mozilla/experimenter/blob/main/experimenter/experimenter/experiments/api/v5/serializers.py#L1044-L1055

We need to do these same things.

[yashikakhurana]

Okay! This is already looking great 🎉 🎉 🎉

Couple things I notice from local testing:

* doesn't display rejection note

* doesn't immediately call remote settings sync

Look at what the V5 serializer does here on save:

https://github.com/mozilla/experimenter/blob/main/experimenter/experimenter/experiments/api/v5/serializers.py#L1044-L1055

We need to do these same things.

@jaredlockhart rejection message not showing up is related to changelog issue and that's why it's not included. I have added all the sync issues which was happening on the serializer to the forms, it should be called immediately now. I will investigate the changelog issue and made a point to implement this rejection message functionality with it.