feat(rollback): Display dismissable banner in sidebar

[malwilley]

With the rollback flag, displays a banner on the sidebar itself to draw attention to the feature. When dismissed, it will display a dot on the org dropdown to show the user that the rollback is still available in the dropdown. Once that is opened, the dot will go away.

https://github.com/user-attachments/assets/9099bd39-3047-4927-8360-ef968954f6d2

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.36585% with 6 lines in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
static/app/actionCreators/prompts.tsx	25.00%	6 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #81061 +/- ## ======================================== Coverage 78.48% 78.48% ======================================== Files 7209 7216 +7 Lines 319477 319652 +175 Branches 43975 44005 +30 ======================================== + Hits 250741 250882 +141 - Misses 62334 62371 +37 + Partials 6402 6399 -3 ```