improve error handling in webRTC-related noise function

[dharjeezy]

Closes #43 This PR:

• eliminates the unsafe assumption and panics in the WebRTC litep2p config when fetching Multiaddr. Ensures litep2p behaves predictably even with malformed or malicious peers during the handshake phase by introducing InvalidMultihash in the AddressError.
• removes assumption about the reply buffer size, by checking the length before splitting in get_remote_public_key function.

I am also looking at other functions to see if there should be any improvement, i will make this a draft PR untill i finish other improvements or if i find no other improvements needed.