feat(manager): no-emit-index-url in pip compile (#15367)

* feat(manager): no-emit-index-url in pip compile

Add support for no-emit-index-url to avoid sharing
confident credentials in the generated requirements.txt
file.

* chore: linting fixes

* chore: update docs

* chore: code review fixes

Co-authored-by: Rhys Arkins <rhys@arkins.net>
Co-authored-by: Michael Kriese <michael.kriese@visualon.de>