Foundry addition

[0xinit]

We can start adding foundry support from here.

Looking at some of the possible ways to integrate it. Anyone else can help out if they want :)

[decafboba]

Would be great for have foundry support!

[decafboba]

@0xinit What exactly is the missing if you were to just replace the root level backend dir with a Foundry contracts structure rather than Hardhat?