feat(nimbus): add application field to rollouts overview form

[moibra05]

Because

• Overview section in new rollouts form was missing the applications field

This commit

• Adds a field to specify application

Fixes #15920

[RJAK11]

I noticed that in the old UI, the Application field is disabled and has the note: “Application can not be changed after an experiment is created.” I was wondering if we should also disable this field in the new UI for consistency but I'm not too sure.

[jaredlockhart]

@RJAK11 is exactly right, we put it there for reference but it's read only and can't be changed 🙏

[moibra05]

ah are we still only going to be able to set the application through the " Create Experiment " modal?

[jaredlockhart]

@moibra05 yeah exactly. On the home page we'll need a new 'create rollout' button that does the same thing, title, hypothesis, application, that creates the rollout, then fill in the rest on the detail page, application field is present but locked.