Add commitment support to MockSubtensor

[agoncharov-reef]

This PR was intended to mock recently-added functions:

subtensor.commit(wallet, netuid, data)
subtensor.get_commitment(netuid, uid)
bittensor.extrinsics.serving.publish_metadata(wallet, netuid, type, data)
bittensor.extrinsics.serving.get_metadata(netuid, hotkey)

In order to "fairly" mock MockSubtensor.commit() and MockSubtensor.get_commitment(), we should mock MockSubtensor.substrate = MockSubstrate(). This way MockSubtensor.commit() will under the hood call bittensor.extrinsics.serving.publish_metadata() which will use our new MockSubstrate - so the behavior will be exactly the same as in production, except that substrate won't make an external call.

However, I see that MockSubtensor does not use any mocked substrate, thus it doesn't use "fair" low-level logic. This leads to following consequences:

1. Low-level functions aren't mocked. One won't be able to test bittensor.extrinsics.serving.publish_metadata and bittensor.extrinsics.serving.get_metadata since there is only "production" substrate class and they use it.
2. High-level MockSubtensor does not really use low-level functions, thus if some low-level function is created/modified/deleted, MockSubtensor will automatically diverge from original Subtensor.
3. MockSubtensor inherits from subtensor, so if any new method is added to subtensor, then new non-mocked method appears in MockSubtensor.

Being said that, I would recommend to mock only real low-level network requests (the SubstrateInterface), so that everything else is mocked automatically now and in the future.

Anyway, taking into account existing codebase and approach, I added MockSubtensor.commit() and MockSubtensor.get_commitment() mocked methods.

Usage:

from bittensor.mock.subtensor_mock import MockSubtensor
from bittensor.wallet import wallet as Wallet

netuid = 9
payload = "some data"

wallet = Wallet(name='mockwall')
wallet = wallet.create_new_hotkey(overwrite=True, use_password=False, suppress=True)
wallet = wallet.create_new_coldkey(overwrite=True, use_password=False, suppress=True)

subtensor = MockSubtensor()
subtensor.create_subnet(netuid)
subtensor.force_register_neuron(netuid, wallet.hotkey.ss58_address, wallet.coldkey.ss58_address) 
subtensor.commit(wallet, netuid, payload)

uid = subtensor.get_uid_for_hotkey_on_subnet(
	hotkey_ss58=wallet.hotkey.ss58_address,
	netuid=netuid,
)
restored_payload = subtensor.get_commitment(netuid, uid)

assert restored_payload == payload

[ifrit98]

Thanks for the PR, LGTM! Are there any associated tests we need to add for this change?

Using MockSubstrate is a good idea. We should incorporate this, however will change a lot of the bespoke existing test logic we have established using the current structure, but will be worth the effort. Openly welcome more PRs! (Added this to the backlog into a planned mocking/testing overhaul).

P.S. In the future, would you mind branching off from staging so we can streamline the inclusion process? Nice job!

[agoncharov-reef]

@ifrit98 Thank you! Agreed.
I will branch off from staging onwards, sorry for confusion.