Add address labeling function to wallet menu

[Reckless-Satoshi]

Labeling addresses comes very handy from time to time. It is not so handy if one needs to re-dicover the CLI command everytime :D

Add a new option to Wallet menu: OPTIONS+=( ... LABEL "Edit address label" ... ). Just a simple shortcut to python wallet-tools.py <wallet_path> setlabel <address> <label> (must prompt the user for an address and a label)

More context in https://github.com/JoinMarket-Org/joinmarket-clientserver/pull/1015