📣 Adding Announcements and Channels

[rapterjet2004]

• fixes 📣 Android: Announcement and Channel presets #6415

🚧 TODO

• test channel usage
• test channel creation - doesn't seem to be working right.

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
• 🔙 Backport requests are created or not needed: /backport to stable-xx.x
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/30644556404/artifacts/8799264492
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)