* feat[message-relayer]: relay tx generator

* whoops, I burned our infura key

* fix minor bug

* add comments

* add more comments and clean stuff up

* add empty test descriptions

* add tests

* move smock to dev deps

* chore: add changeset

* minor cleanup to merkle tree proof function

* use bignumber math to avoid nested await

* use a better interface

* minor fixes and simplifications