[Improvement]: Include All API Params for Announcement + Reimplement isRead feature

[azooz2003-bit]

Description

The Announcement model only contains a small subset of properties. Notably, it omits the read_state. Extend the model to include all properties as show in the link below.

Replace the existing isRead feature with the value provided by read_state.

Relevant Resources

(Feature Owner, Developer) Attach links to resources such as Figma files, technical documentation, etc.

• API Docs: See the Discussion Topics API, it shows you the full object returned by the announcement query.
• Canvas iOS: This is the Canvas iOS repo. In case you want to see how they did it.

Child Issues

(Developer) Add child issues (technical or high level) that will help you modularize your implementation this feature.

• Task 1 ...
• Task 2 ...

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Implementation Plan (optional)

(Developer) Write an implementation plan here, or attach a link to a document containing it.