Move EventTileBubble to shared components

[rbondesson]

Checklist

• I have read through review guidelines and CONTRIBUTING.md.
• 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.
• I have licensed the changes to Element by completing the Contributor License Agreement (CLA)

Move EventTileBubble to shared-components

Summary

• Moved EventTileBubble component to @element-hq/web-shared-components package as EventTileBubble

Changes

New shared component

Added EventTileBubble under packages/shared-components/src/event-tiles/EventTileBubble/ with:

• CSS module for styling
• Storybook stories for visual testing
• Unit tests with snapshot coverage

Codebase migration

• WaitingForThirdPartyRoomView.tsx: Now renders EventTileBubble instead of the old component
• EncryptionEvent.tsx: Now renders EventTileBubble instead of the old component
• MJitsiWidgetEvent.tsx: Now renders EventTileBubble instead of the old component
• MKeyVerificationRequest.tsx: Now renders EventTileBubble instead of the old component
• RoomPredecessorTile.tsx: Now renders EventTileBubble instead of the old component
• HistoryTile.tsx: Now renders EventTileBubble instead of the old component
• NewRoomIntro.tsx: Now renders EventTileBubble instead of the old component
• Moved the css global variable --EventTileBubble_margin-block: 10px; to _common.pcss
• Changed font-size for subtitles from $font-12px (0.75rem) to --cpd-font-size-body-sm (0.8125rem) - there is no equivalent font size in compound.
• Changed padding for the container from 10px to --cpd-space-3x (12px) - there is no equivalent padding in compound.

Test plan

• Verify event tile bubble renders correctly in rooms
• Run new unit tests: yarn test:unit "EventTileBubble" -u
• Run unit tests for affected components in element-web
• Check Storybook stories render correctly

Tests

Before & After

• Before Refactoring

• After Refactoring

[t3chguy]

Looks generally sane other than the nits