feat: group timeline events by relative dates

[tianrunhe]

Description

Fixes this bet:

The “Scrum Knights” found our Timeline view to be cluttered. Let’s improve its organization by adding headers that group activities by time. Ideally we can determine an appropriate header frequency when presenting the meeting history (days, weeks, or months) dynamically.

Demo

Testing scenarios

• Grouped timeline

  • Go to http://localhost:3000/me
  • See timeline events grouped by relative date headers

• Locked history

  • Go to http://localhost:3000/me with a starter team & locked histories
  • Scroll down and still see the locked history card

Final checklist

• I checked the code review guidelines
• I have added Metrics Representative as reviewer(s) if my PR invovles metrics/data/analytics related changes
• I have performed a self-review of my code, the same way I'd do it for any other team member
• I have tested all cases I listed in the testing scenarios and I haven't found any issues or regressions
• Whenever I took a non-obvious choice I added a comment explaining why I did it this way
• I added the label Skip Maintainer Review Indicating the PR only requires reviewer review and can be merged right after it's approved if the PR introduces only minor changes, does not contain any architectural changes or does not introduce any new patterns and I think one review is sufficient'
• PR title is human readable and could be used in changelog

[nickoferrall]

Love this! Looks great. I like the emoji choices