Spike: Determine best approach for supporting annotations on metrics dashboard charts

Summary

As a part of our efforts to add annotations to the monitoring dashboard, we should figure out the best way to store and save annotations.

Issue breakdown

First iteration

1. Backend: Basic Implement of annotations CRUD. #211329 (closed)
2. Backedn: Expose webhook create annotation endpoint #211460 (closed)
3. Backend: Expose an endpoint to perform Read operations on annotations. #211330 (closed)
4. Frontend: Fetch all annotations for a dashboard and display them on all charts. #211418 (closed)
5. Spike/Discuss best approaches to store and perform CRUD operations on annotation tags. #211426 (closed)

Second iteration

1. Backend: Expose an endpoint to perform CUD operations on annotations. #211461 (closed)
2. Frontend: Create a UI to create annotations
   1. Clicking on a monitoring chart should show popover menu to create annotation (#211419)
   2. Display a form to create annotation from the chart popover menu (#211425)
3. Backend: Basic implementation of annotation tags CRUD. #211429

Third iteration

1. Frontend: Fetch annotations for a panel #211432
2. Backend: Create a reaper job to remove all annotations older than 14 days. #211433 (closed)
3. Frontend: Edit/update/delete annotations through UI. More focus on tags editing and creating. #211434

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@ClemMakesApps @mnohr, we should discuss together with other members of the team, please add your thoughts