Generate sub-sub-commands for the transaction factories

[andreibancioiu]

Existing transaction factories:

• https://github.com/multiversx/mx-sdk-py-core/tree/v0.7.4/multiversx_sdk_core/transaction_factories

If possible, it would be nice to add CLI support for creating transactions using the intent factories.

Dynamically get functions of intents factory class, dynamically get arguments of factory functions, generate sub-commands for the argsParser etc.

In the end, we could have something like:

mxpy tx-factory (or something like that) delegation new_delegation_contract --total_delegation_cap=... --service_fee=... --pem=... --proxy=... --send

References (maybe useful, maybe not):

• https://stackoverflow.com/a/39061905/1475331
• https://stackoverflow.com/a/4051447/1475331