[PR] Multihash initial implementation

[LuchoTurtle]

loosely related to #1

This PR doesn't address #1 but implements a prerequisite of it: Multihash.

I've noticed there wasn't a Dart implementation for Multihash -> https://github.com/multiformats/multihash#implementations, which is a shame since Dart is increasingly being used.

This PR will basically necessitate changing the scope of this repo to a library that offers Multihash capabilities to Dart instead of building a CID. We are going to use this to build the CID on a different repo though, for sure :).

It's still in progress because I want to refactor and iron out the package so it offers similar capabilities to https://github.com/multiformats/js-multihash, https://github.com/multiformats/py-multihash, and https://github.com/multiformats/ex_multihash.

[LuchoTurtle]

@nelsonic I guess Signal is not working there but I mentioned in the standup I was wanting to change this repo to be the multihash one and I'd eventually create the cid on a different one, since it's easier for me to maintain the versioning of the changes made.

Since you already went thru the effort of creating the multihash one, I'll find a way of cherry picking these commits to another PR there, np 👍

[nelsonic]

You don't have to cherry-pick anything. Just merge the two repos: https://stackoverflow.com/a/10548919/1148249 Should take less than 1 minute.

Again, none of this would be required if you followed my "We Don't Need Multihash" request ... 😜

[LuchoTurtle]

@nelsonic I fail to see why we should merge the two repos, why did you create the other one? No matter, don't worry about it 👍

Again, none of this would be required if you followed my https://github.com/dwyl/dart_cid/issues/1#issuecomment-1326475907 ... 😜

As for this, you are right and I'm committed to do overtime so it will even out, I promised ;)