External $ref

[jayvdb]

Describe the bug
If a $ref refers to an external document, cherrybomb panics with "external references are not supported yet.."

To Reproduce
Steps to reproduce the behavior:

1. Create an open $ref to link to another file
2. Run cherrybomb on the openapi file
3. See error

Expected behavior
cherrybomb reads the external doc.

[jayvdb]

One way to reduce the impact of this is to add pub to run_profile_info etc, so that I can load the OAS myself, and then invoking those inner functions with the loaded doc.