[stable29] chore(release): Add changelog for Talk 19

[backportbot]

Added

• Messages can now be edited by logged-in authors and moderators for one day #1836
• Allow todo lists in chat messages to be interactive #12065
• Added a "In conversation" search filter #11456
• Save unsent messages in browser storage so they survive a page reload or browser restart #3055
• Allow to accept individual users when the lobby is enabled #8601
• Flavored Markdown in messages #10066
• Allow to see all reactions #11508
• Preview: Federated chatting #11231

Changed

• Update translations
• Update several dependencies
• Added support for Janus 1.x
• Prepare frontend code for a migration to Vue3
• Migrated various icons to Material Design icons
• Deleting messages is now possible without a time limitation (was 6 hours) #11408
• Guests are now rate-limited on mentioning users #11072
• Make polls more visible in the chat when they are posted during a call #11372
• Bots can now be installed by apps with limited feature flags #11630
• Save all previously picked devices to improve the call experience when switching between different working situations #12067

Deprecation

• Commands: This will be the last major version that supports commands. Please migrate your commands to webhook based bots instead.