Consider removing `get_procedure_root` and `get_num_procedures`

I think my main concern is adding new kernel procedures that for now, are only needed in this particular context. Especially, adding `get_procedure_root` means we commit the tx kernel to an `index |-> MAST_ROOT` representation of account code, or at least one that can translate an index to a MAST ROOT. These procedures are relatively simple and so I'm not overly concerned that this is impossible, but my larger point here is that every kernel procedure we add needs to be maintained forever and cannot be removed once we go to mainnet, and so I simply want to be careful about what we really need and what we commit to :slightly_smiling_face: Adding a kernel procedure later is easy and non-breaking; removing one is impossible. And so in that context, I think the main benefit of the "unhashing into memory" approach is that it avoids the need for both of the new kernel procedures.

I'm still fine to go ahead with this approach if you both think it's fine. If this component turns out to be rewritten, it'd still be nice to reconsider the need for these kernel procedures.

_Originally posted by @PhilippGackstatter in https://github.com/0xMiden/miden-base/pull/1968#discussion_r2425547487_