[FEATURE] Annoucement feature for admins

[vinitkumar]

Is your feature request related to a problem? Please describe.
A new feature called as Announcement that will let the admin post a message that will be visible to all users of the platform as they log in.

Describe the solution you'd like
The feature will let the admin create a new announcement containing a title and a body and that gets rendered on the top.

Describe alternatives you've considered
No alternatives considered, it's a new feature.

Additional context

• More details to follow