feat: Add announcements system

[beebls]

Please tick as appropriate:

• [ ] I have tested this code on a steam deck or on a PC
• [ ] My changes generate no new errors/warnings
• [ ] This is a bugfix/hotfix
• [x] This is a new feature

If you're wanting to update a translation or add a new one, please use the weblate page: https://weblate.werwolv.net/projects/decky/

Description

This fixes issue: #672

Adds an Announcements (formerly MOTD) display to the root QAM view,

The [plugins/testing].deckbrew.xyz/v1/-/announcements/current endpoint is used, and the latest announcement from this endpoint is display in the QAM.

Upon clicking the X button, that announcement's id is added to a hidden announcements list so that it isn't displayed again