DSC/CSCA verification - prover

[remicolin]

Add two major features:

• DSC verification against CSCA - sha256 with RSA encryption, key length < 4096 bits
• prover running on Modal server to generate the DSC verification proof

Other implementations:

• creation of splitBytesToWords and splitSignalsToWords circuits
• update of leaf generation with new leafHasher circuit
• new scripts for registry
• update of contracts test logic
• add mock dsc/csca certificates

[remicolin]

close #37 for sha256 with rsa encryption csca certificates with a key < 4096 bits