Allow main as default channel

[mashehu]

Closes #1931

Tasks

Beta Give feedback

1. switch tools repo to main
2. switch modules repo to main (build in logic to check default branch early, make switch later)
3. switch configs repo to main
4. update pipeline_health page
5. test-datasets (should be easy?)

[ewels]

Configs: Can rename to main but then create a master branch that has just the nfcore_custom.config file there which then in turn redirects to the correct file on main.

Also need the pipeline includes.