Add enter / exit / transfer commands to CLI

[maaktweluit]

Add CLI commands, GSB messages and driver implementation stubs for:

yagna payment enter --driver=zksync --network=rinkeby
yagna payment exit --driver=zksync --network=rinkeby [optional address]
yagna payment transfer —driver=zksync —network=rinkeby [address]

[Wiezzel]

Parsing amount should be done in CLI, not in driver.

[maaktweluit]

@Wiezzel Was unsure about amount, since it will be put into a string when send over GSB anyhow...

Will update it to parse earlier :)

[pnowosie]

Great work!