Feature/delegate wallet passthrough

[acedward]

        delegate                = &wd|from?|to?|from_signature|to_signature
        migrate                 = &wm|from?|to?|from_signature|to_signature
        cancelDelegate          = &wc|to_signature

if valid wallet-delegate commands are now passed to the SFT.
Valid means the signatures are correct, and the command could be processed and was not rejected.

[SebastienGllmt]

What happens if the user's STF doesn't have something to parse this? What happens if the name conflicts with something else the user defined in their STF

[acedward]

1. If the user does not have the parser setup, a console error will show up, but not halt paima-engine. (same error if a user posts any invalid command directly to the blockchain)

2. Conflict is unlikely as the command starts with the symbol & as described in the documentation.

[SebastienGllmt]

Okay, this may be a bit messy until we make STF failure more local instead of failing full txs, but we don't need to block this PR on that