Automatic use of local version when `requires: ..` is used

[jayvdb]

With a mobanfile containing

requires:
  - https://github.com/django-mobans/docker-mobans

- configuration:
    configuration: .moban.yaml
    template_dir:
      - 'docker-mobans:.moban.dt/'

If I want to test an un-merged change to docker-mobans, I need to edit the mobanfile to look for a local version

- configuration:
    configuration: .moban.yaml
    template_dir:
      - ../docker-mobans/.moban.dt/

It would be nice to have a way to do that change without editing the mobanfile.

The way that would be most suitable for the way we have been setting up repos recently is to convert

'docker-mobans:.moban.dt/' -> ../docker-mobans/.moban.dt/

however iirc pyexcel often has the local version as submodules so that would mean

'docker-mobans:.moban.dt/' -> ./docker-mobans/.moban.dt/

This use of a local version could be triggered with a cli flag like --local-requires

Ideally any modified target includes a header comment describing the different source which was used, but moban doesnt know how to do comments in every language, so that needs to be a separate enhancement, and there are a few quite-old issues which relate to this.