v2.4.4-rc.1

Full Changelog

• Fix SAS verification in encrypted DMs
  #1077
• Cross-signing / secret storage tweaks
  #1078
• Fix local trust for key backups
  #1075
• Add method to get last active timestamp in room
  #1072
• Check the right Synapse endpoint for determining admin capabilities
  #1071
• Cross Signing Support
  #832
• Don't double cancel verification request
  #1064
• Support for verification requests in the timeline
  #1067
• Use stable API prefix for 3PID APIs when supported
  #1066
• Remove Jenkins scripts
  #1063