Augment Get-IshDocumentObj with protocol OpenApiWithOpenIdConnect implementation

[ddemeyer]

Summary...
Modernize the cmdlet by adding OpenApiWithOpenIdConnect implementation next to already implemented and working WcfSoapWithOpenIdConnect/WcfSoapWithWsTrust. The only experimental implementation we have is in AddIshFolder.cs where we have a switch (IshSession.Protocol) sample to show side-by-side implementation.

The idea is that the existing cmdlet and its parameter groups remain exactly the same, so backward compatible. It is only an internal change to enable an extra backend. This also means that the ISHRemote objects structures like IshFields, IshMetadataFilterField, IshRequestedMetadataField need to be mapped internally to the new OpenAPI. Also the output objects like IshObjects, IshMetadataField remain the same. Users of the ISHRemote library should not see the difference, and do not get any breaking change.

Actions...
Start with the below so we can have a debug working call to OpenAPI

• Adapt GetIshDocumentObj.cs and potentially OpenApiISH30EnumerationsExtensions.cs section for enumeration conversions to do the request. Same for IshFieldsExtensions.cs
• Use OpenAPI IshSession.OpenApiISH30Client.GetDocumentObjectListByLogicalIdAsync function as alternative for already used IshSession.DocumentObj25.RetrieveMetadata

Once we have the working call, human approved, we can further and adapt the conversion to IshObject pipeline objects.

• Adapt new IshObjects(ISHType, xmlIshObjects); with an overload that can convert the OpenAPI (json) objects returned by the API into the ISHRemote public pipeline objects.
• Use OpenAPI IshSession.OpenApiISH30Client.GetDocumentObjectListByLanguageCardIdAsync function as alternative for already used IshSession.DocumentObj25.RetrieveObjectsByIshLngRefs
• Extend GetIshDocumentObj.Tests.ps1 with comparison tests. Dynamically changing from $ishSession.Protocol=WcfSoapWithOpenIdConnect to $ishSession.Protocol=OpenApiWithOpenIdConnect and back allows to test the result of both code paths, so both the Soap and Rest/OpenAPI backend. There should be a shallow result compare and perhaps a performance test variation.