Cleanup loader workspace after each run

Cleanup private action workspace after each use (#6)

Cleaning up private action workspace after run so that it can be reused multiple times

Fixing input validation issue

This release properly enforces required inputs as well as applies default values where configured.

Load private actions in any repo

v1 allows loading private javascript actions in any repository.

    - uses: invisionapp/private-action-loader@v1
      id: example
      with:
        repo-token: ${{ secrets.PRIVATE_REPO_TOKEN }}
        repo-name: some-org/super-secret-action@v1 # SHA, branch, tag, or no ref can be specified
        # inputs gets passed to the private action
        input-used-by-private-action: this will be passed to super-secret-action
    - name: Get the previous output
      run: echo "The previous output was ${{ steps.example.outputs.<name of output> }}"