Shashank madan pr grading screen backend

[shashank-madan]

Description

Related PRS (if any):

This backend PR is related to the #4533 frontend PR.

Main changes explained:

• Added Pages for PR Grading dashboard
• Implemented logic to allow only valid pr numbers as inputs
• Added dark mode styling to all pages in pr grading dashboard

How to test:

1. check into current branch
2. do npm install, npm run build and npm start to run this PR locally
3. Clear site data/cache
4. log as owner user
5. go to http://localhost:5173/pr-grading-dashboard
6. Add a new reviewed PR to one of the reviewers
7. Add a new reviewer
8. Click Save
9. Verify that you get toast messages indicating success at the steps.
10. Refresh the page and verify that your changes have persisted
11. Check dark mode as well

Screenshots or videos of changes:

PR-grading-dashboard.mp4

[Anusha-Gali]

Hi Shashank,

I have reviewed your PR locally and the backend works as per requirement.