[dev]: Enumerate functionality changes necessary to ensure watchtower channel defense for taproot asset channels

[dstadulis]

Is your feature request related to a problem? Please describe.
Given preliminary taproot channel support in lnd lightningnetwork/lnd#7733 enhancements will be necessary to perform and test watchtower support for Taproot Asset channel state.

By design, channel state uploaded to watchtowers doesn't include inflight HTLCs which reduces the complexity of delivering support.

TODO:

• Enumerate functionality changes necessary to ensure watchtower channel defense for taproot asset channels