Parse gates before proving

[AllFi]

This pull request adds the feature to decompress and parse gates prior to the proving process. The reason why this can be useful is described in the issue.

The interface of Parameters has been extended with the following methods:

• precompute - this method decompress and parse gates
• precompute_memory_size - this method evaluates the required memory size (in bytes) for precomputed data
• get_witness_rcs_precomputed - this method creates a witness that utilizes pre-parsed gates during the proving process

The function prove_precomputed has been added to use pre-parsed gates during the proving process.

GateSource, GateIterator, GateWrapper have been implemented to support both approaches during the proving process without unnecessary clones.