Add SOAP WSDL as API Service

[chrisrayrayne]

Is your feature request related to a problem? Please describe.
A lot of APIs are still SOAP-based, especially the legacy world but not entirely. As of now, only REST APIs can be added.

Describe the solution you'd like
Add SOAP like RESTful but parsing WSDL instead of a OpenAPI-specification

Describe alternatives you've considered
Instead of parsing WSDL, there is also the possibility to convert WSDL to OpenAPI and parse like before.

Additional context
Converter (not tested): https://github.com/anhthang/soap-converter