PalletId-based subnet account Ids maintain subnet TAO reserves

[gztensor]

Description

• Every subnet will have an account ID and the subnet swap pool reserves will be stored in subnet account balance.
• The subnet account ID is derived from SubtensorModule account ID and does not have a private key, so no transactions may be initiated by this account.
• Use of subnet account IDs as hotkeys for staking, registration of neurons, or as a subnet owner hotkey will be forbidden.

Checklist:

• Derive subnet account IDs
• Create runtime API subnetInfoRuntimeApi::getSubnetAccountId for clients to read the subnet account IDs
• Deprecate SubnetTAO map, migrate TAO stored in SubnetTAO into subnet accounts. This will make balances pallet TotalIssuance match the subtensor pallet TotalIssuance.
• Use subnet accounts as subnet reserves for Alpha <> TAO swaps.
• Use subnet accounts for injecting of newly minted TAO in run_coinbase.

Related Issue(s)

• Part of Use imbalances to maintain TAO emission and burning #2403

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Breaking Change

The SubnetTAO map will be removed. Instead, clients should use subnetInfoRuntimeApi::getSubnetAccountId to get the account ID of the netuid reserve and then pallet_system::account to get the account balance.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run ./scripts/fix_rust.sh to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Screenshots (if applicable)

Please include any relevant screenshots or GIFs that demonstrate the changes made.

Additional Notes

Please provide any additional information or context that may be helpful for reviewers.