initial News Pallet

[CrackTheCode016]

This PR adds the initial version of the news pallet for EduChain. It allows publishers to record news articles on-chain and verify their signatures.

Features:

• Store article metadata and signatures.
• Map articles to publishers and collections.
• Limit the number of articles per publisher.
• Verify article signatures using the publisher’s account.

Dispatchable Calls:

• record_article: Record a new article.
• update_article: Update the article on-chain.

Events and Errors:

• Emits events for article recording and verification.
• Handles duplicate articles, invalid signatures, and storage limits.

[CrackTheCode016]

@midegdugarova A little more context - so the role of this pallet is to aggregate info about the article. It's assumed that they would've created the NFT collection / item first - so the flow is like this:

• Create identity on People Chain
• Create NFT on Asset Hub
• Register article here in this pallet

The frontend is what brings this together, showing how you can compose an app using multiple chains, yet having them still work together. Obviously one could use the pallet in isolation - but it wouldn't be very useful, as the frontend will cross-check the identity and existence of the NFT on Asset hub to ensure legitimacy.

Of course, the next step could be actually verifying some of this state in the runtime, but this is probably good enough for the purpose of showing a basic pallet