[feature]: Enhance channel funding by passing asset specified by a group key

[dstadulis]

In line with developing universal-group-key support, channel funding will need to be augmented the channel-funding sequence

This work will entail:

• [ ] Upgrading tapd's custom-channel channel funding processes
• [ ] Upgrading lnd to handle any additional arguments/information associated with the group key data structures
• [ ] Adding tests to litd to try to {in,}validate this new functionality.

This issue will precede #1028