Feature request: Support actions monorepos

[fbonander]

I would be great if this action would support monorepo setups. We currently have a monorepo that have a large number of actions and reusable workflows.

I'm thinking something like this:

 - name: Publish
      id: publish
      uses: actions/publish-immutable-action@0.0.3
      with:
         files-pattern: ./actions/java/unit-tests/**
         name: java/unit-test

And then for consumtion:

- uses: your-name/mono-repo/java/unit-test@v1

[grahame-student]

This looks like a duplicate of #217