[create] Option to work with other SCM providers (GitLab, BitBucket etc)

[ewels]

We love GitHub at nf-core, and the nf-core template will always default to using GitHub features. However, as we think about making the template more user-friendly for people creating pipelines outside of the nf-core organisation, it could be nice to make life easier for people working with other platforms.

• Opt out of .github files
• Alternative dotfiles for issue templates etc for GitLab, etc.

Collect additional specifics in this issue please..

[awgymer]

GitLab:

• Issue/MR templates do not allow for html form style we use in GitHub. Will need to potentially rework wording/layout
• CI/CD does not offer catalog of reusable components (e.g. no GitHub actions equivalent)
• CI/CD does not allow for easily passing output from one job as an input map for next job (e.g. the way modules repo currently uses the glob to detect altered modules)