Publish ark-zkey module as a library on Crate.io

[seemenkina]

Problem

The mopro project currently works under a patch to the wasmer library. This patch causes a conflict and overrides dependencies when using mopro as a submodule if wasmer is also used in the other project. At the same time ark-zkey module does not require a wasmer, but because it is part of the mopro project you have to connect the whole project.

Suggested solution

To address this issue, I suggest isolating ark-zkey module as a library and publishing it separately. It provides easy use of its functionality to everyone.