feat: able to compute epoch proof quote digest in typescript

[just-mitch]

Presently, users need to query the rollup contract in order to produce the digest.

It would be nice if they didn't need to do this.

The reason they do, is they need to know the EIP712 domain separator information from the rollup contract.

So they should be able to query for the separator information from the rollup contract (which they can currently) once at startup.

Then they should be able to produce the digest in typescript.

[LHerskind]

Not needed after the move to multiproofs.