Use crossplane-runtime Reference type for provider references

[hasheddan]

Description of your changes

This updates all provider references to use the crossplane-runtime Reference type in order to avoid errors from a user supplying an extraneous namespace in their provider reference.

Signed-off-by: hasheddan georgedanielmangum@gmail.com

See https://github.com/crossplane/provider-aws/pull/264

Checklist

I have:

• [x] Run make reviewable to ensure this PR is ready for review.
• [x] Ensured this PR contains a neat, self documenting set of commits.
• [ ] Updated any relevant documentation, examples, or release notes.
• [ ] Updated the dependencies in app.yaml to include any new role permissions.
• [ ] Updated the package resources documentation to include any new managed resources or classes.