devcontainers
`devcontainer features test` should log install output
devcontainer features test is great for black box tests / end result tests of install.sh.
However I also want to make sure what the script does exactly, i.e. whitebox-test or interaction-test.
For example when java is already available, I want my script to not install default-jre as that's kind of stupid.
I cannot verify this via the end result, as it's always the same: java is available.
Of course I could write some file from my install script with such information, e.g. when a debug option is set to true.
However I don't want to have such an option in my feature?!
It does seem easier if the docker image as generated by devcontainer features test would RUN the script with | tee install.log?
Then it doesn't end up in the final feature and I could check the contents of install.log from test.sh.
