L2: prove L2 deposits

[xqft]

First add the committed deposit logs hash as public input to the execution program of each zkvm. Then, in the program:

1. For each PrivilegedL2Transaction in the block (transaction type used exclusively for deposits):
   1. Recreate the deposit log from the transaction fields (value, to, deposit_id)
   2. Push the log into an outer vec
2. Hash the log vec (the same way the committer does). This should be the committed deposit log hash.
3. Check that the resulting hash equals the public input one.