Dockerize test env
🚀 Feature
the simples way for speedup builds is have a docker image with all dependencies then preserving pip cache, that means we will create a docker image which will be pulled
Motivation
for that, the simples way is hawing it id docker hub as it is a native location for almost all CI
these "devel-lightning" docker images can be simply used by any contributor for testing lol
Pitch
we may also have a docker image with installed lightning and all requirements which would make the starting with lightning even easier and it would be also useful for people working on a production
Alternatives

Additional context
later I may configure a cron do this docker build every week