Add --profile flag to nf-core modules test to allow CLI speification of container/conda engine

[jfy133]

Description of feature

It would be nice to skip having to select the container engine /env software option when running tests.

This is work aroundable by specifying PROFILE=singularity before the command for example, but I find that is not natural usage when executing flag based CLI tools that otherwise the nf-core package is.

One other alternative is to add a .nfcorerc file or similar that goes into home, and one can permanently set such an option, and if the file/option is detected, the -d.
I don't

[mirpedrol]

Done with #2767