Import from URL doesn't respect Validate Certificates setting

**Describe the bug**
The Import from URL feature fails on an invalid certificate with the (not entirely helpful) error message: "Import Failed" "TypeError: Failed to fetch".

Inspection in the developer tools indicates a net::ERR_CERT_AUTHORITY_INVALID error for the request.

**To Reproduce**
Uncheck the Validate Certificates setting. Attempt to download wsdl from an in-development API using a self-signed or otherwise invalid certificate.

**Expected behavior**
WSDL imported successfully despite invalid certificate (when Validate Certificates is unchecked)

Trace the Import from URL entry point and the Validate Certificates setting through the request path, using the developer tools certificate error as the starting symptom. Reproduce with a WSDL endpoint using an invalid certificate: importing should succeed when validation is unchecked and remain rejected when it is enabled.

Written by the indexing model from the issue text.