v12.1.0-rc.1

Full Changelog

• Add VS Code to gitignore
  #1783
• Make Crypto::inRoomVerificationRequests public
  #1781
• Call setEventMetadata() for filtered timelineSets
  #1765
• Symmetric backup
  #1775
• Attempt to fix megolm key not being in SSSS
  #1776
• Convert SecretStorage to TypeScript
  #1774
• Strip hash from urls being previewed to de-duplicate
  #1721
• Do not generate a lockfile when running in CI
  #1773
• Tidy up secret requesting code
  #1766
• Convert Sync and SyncAccumulator to Typescript
  #1763
• Convert EventTimeline, EventTimelineSet and TimelineWindow to TS
  #1762
• Comply with new member-delimiter-style rule
  #1764
• Do not honor string power levels
  #1754
• Typescriptify some crypto stuffs
  #1508
• Make filterId read/write and optional
  #1760