Message Pinning: rework the message pinning list in the right panel

[florianduros]

Checklist

• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• Sign-off given on the changes (see CONTRIBUTING.md).

Figma: https://www.figma.com/design/nwbnk8RaZctjrrRGTUcx1X/Pinned-Messages?node-id=38-163717&t=QpPa8ByPpyclY6Wq-0
Part of https://github.com/element-hq/element-internal/issues/600 & https://github.com/element-hq/element-internal/issues/608

The PR can be reviewed commit by commit.
The content is the rework of the message pinning list in the right panel:

• Rewrited completely the PinnedEventTile to match figma design and behavior
• Refactored and documented PinnedMessagesCard
• Extracted the logic of the message pinning list inside PinnedMessages
• Rework existing tests and improved the code coverage
• Added e2e tests

[t3chguy]

In future please avoid force pushing after a review was made as now I can't just review the diff since my last review

[florianduros]

@t3chguy Raaah I used git absorb to make the history cleaner, will do it after the review