Create wrapper contract for NMT

[adlerjohn]

Now that we have the implementation of the multiproof, does it make sense to create a separate contract that calls it? And we generate a go wrapper for this latter so that we use it in the verification command we're planning to have for the QGB?
If so, I can create an issue and start working on it.

Originally posted by @sweexordious in #131 (review)

[rach-id]

We should implement the following: https://github.com/celestiaorg/celestia-core/blob/3f3b7cc57f5cfc5e846ce781a9a407920e54fb72/types/share_proof.go#L62-L99 in this contract