zk-census-proof: update processID approach

[arnaucube]

• Change from electionID to processID
• Update circuit input of the processID to be an array of 2 big integers obtained from the 32-byte array that is the processID

This change is done as @ed255 pointed out that the processID is not a number itself, as it is the 32-byte output of a hash. The change in this PR applies a similar approach used for the voteValue but for the processID.