Update `lightninglabs/loopserver`/`regtest`

**Is your feature request related to a problem? Please describe.**

Currently `lightninglabs/loopserver`/`regtest` does not support Static Loop In Addresses or Instant Loop Outs.

**Describe the solution you'd like**

Updating `lightninglabs/loopserver` would be very helpful for testing these features.

**Describe alternatives you've considered**

N/A

**Additional context**

I'm working on an alternative Loop server, I'm testing against the `lightninglabs/loopserver` to ensure compatibility.

Start by locating the lightninglabs/loopserver/regtest entry point and reviewing how Static Loop In Addresses and Instant Loop Outs are currently represented. Confirm the compatibility expectations for both features, then verify the regtest setup supports them against the alternative Loop server.

Written by the indexing model from the issue text.