Create Dashboard with PR-Level Review & Comment Tracking, Filtering, and Metrics

[kokerinks]

Is your feature request related to a problem? Please describe.

Reviews and comments play a crucial role in project development. To better track contributions, we should include them as a metric.

After further discussion from #447 , it is agreed that the user should have a PR-level view of each PR within the repo. Hence, the design of the dashboard has been improved to show this.

Describe the solution you'd like
@NorbertLoh and I have redesigned the dashboard as such:

The features of the dashboard is as follows:

• shows the timeline of reviews/comments per PR, and who is responding to who during the PR lifetime
  • team members are represented by the colored circles, each one represents a comment or PR within the timeline
• shows the sum of reviews/comments contributed per member, per PR
• tallies up the total at the end of the table to give a repo-level view of reviews/comments made per team member

Users can also choose to filter this table based on a few conditions. Some possible filters in mind are:

• Creator of PR (filters PR rows based on creator)
• Time frame (range filter, user can specify start and end time for timeframe)
• Milestones

Additional context
This may be a rather complex feature, if there is anything I can clarify further in my explanation feel free to let me or @NorbertLoh know! Any other suggestions will also be greatly appreciated. Thanks!

EDIT:
For now, @NorbertLoh and I intend to work on this feature away from main branch, and hence will make our PRs to reviews-dashboard branch instead. We will create a PR to merge the full feature to main once it is completed.

[damithc]

@kokerinks Let's go ahead and see how it turns out.

BTW, we can probably show the total at the top (together with the user avatar) rather than at the bottom.
PR author can be shown on the left.