🚀 Feature: Migrate reusuable components to `announcements-react`

[kurtaking]

🔖 Feature description

Several components can be migrated to the new announcements-react package.

🎤 Context

This is to support the new Backstage architecture and package conventions. From my understanding, the following components should (can?) be migrated.

• AnnouncementSearchResultListItem
• AnnouncementsCard
• AnnouncementsTimeline (?)
• NewAnnouncementBanner

✌️ Possible Implementation

These components should be copied to annoucements-react and deprecated in announcements.

👀 Have you spent some time to check if this feature request has been raised before?

• [X] I checked and didn't find similar issue

Are you willing to submit PR?

Yes I am willing to submit a PR!