Split lnd into a separate repo

[meeDamian]

Right now lnd provides its own Dockerfile, however there are some issues with it:

1. provided Dockerfile does not specify tag/version, and always builds from master which is terrible for us if we want any sanity of debugging
2. it unnecessarily installs bash in the final stage
3. it unnecessarily clones entire repo with its history

This issue can be closed when:

• there's a new repo lncm/docker-lnd
• repo is set to have automated amd64 build on Docker Hub
• all lnd stuff is removed from lncm/dockerfiles
• arm builds are somehow addressed (either by figuring out how to skip apk add ca-certificates, so Go's native cross-platform builds can be used, or qemu, or manual RBP builds a'la bitcoind)