Discussion with onchain data #76

[manlikeHB]

Closes #76

• [x] Implement discussion component with add and retrieve comment functions
• [x] should depend on the Proposals component for fetching live proposals
• [x] Update tests in tests/proposals.cairo

[manlikeHB]

@tensojka This is what I have so far.

[manlikeHB]

Hi @tensojka, my PR is ready for review.