Fixes broken e2e tests

[thewhaleking]

see: #3019

Fixes test_subtensor_extrinsics by correctly calculating the extrinsic fee.

Comments out the broken part of test_batch_operations with an explanation as to why the calculation is not possible for that test.

Adds calculation of the fees within the unstaking extrinsics (sync and async), as well as outputting this fee in the logger.

Adds TODO questions for the unstake method for both Subtensor and AsyncSubtensor enquiring as to why the netuid arg is Optional[int] rather than int.

Should unblock e2e failures.

[thewhaleking]

Still sometimes failing flaky tests (see #3015), but that's not the point of this PR.

[basfroman]

Looks good, but let’s move all the fee calculation logic into utility modules within the extrics sub-packages, so it can be reused from a single place and follows the DRY principle.

[basfroman]

Still flaky tests:

• tests/e2e_tests/test_liquidity.py - fixed
• tests/e2e_tests/test_staking.py - subtensor related issue