API Doc : URL reported to Ambassador Cloud is wrong

[shepz]

Describe the bug Emissary automatically adds the prefixes from the mappings to the swagger APIs on the fly. The issue with that is that sometimes, the swagger contract already contains a base path. As a solution, we should also read the rewrite field from the mapping, and avoid adding the prefix if it matches the rewrite.

See code : https://github.com/emissary-ingress/emissary/blob/master/pkg/agent/api_docs.go#L273

To Reproduce Steps to reproduce the behavior:

1. Connect your Cluster to Ambassador Cloud
2. Deploy an application that reports an APIDoc with a base path.
3. Create a mapping that point to the APIDoc created. Mapping must include a prefix
4. Navigate to Service Catalog choose your service and click on the API Tab

The URL reported includes the mapping prefix and the basePath.

Mapping Host : my-website.com Mapping Prefix : /hello BasePath in swagger : /hello

Url reported in the UI : my-website.com/hello/hello

Expected behavior Don't add two times the prefix if it's the same

Versions (please complete the following information):

• Ambassador: any
• Kubernetes environment : any
• Version : any

Additional context Add any other context about the problem here.