fix: Fix and refactor Timeline component in trame

[jafranc]

This PR aims at making a workable Timeline component in trame UI that will:

• Allow user to see the following Periodic events on a Gantt-like charts of different colors:

1. Solvers
2. Output
3. Statistics

• Introduce appropriate datetime algebra when it comes to duration and date computes, though ensuring string representation where it is mandatory
• Re-think the timeline peek view (to something clearer)
• Fix or discard Date picker (TBD)