Add API Endpoints for Commerce

[infofromca]

Try to fix #450

[sarahelsaig]

You can check the static code analysis locally by typing dotnet build OrchardCore.Commerce.sln --configuration:Release --nologo --verbosity:quiet --warnaserror --warnAsMessage:MSB3026 --consoleLoggerParameters:NoSummary -p:TreatWarningsAsErrors=True -p:RunAnalyzersDuringBuild=true into the console.

[infofromca]

@sarahelsaig I just Simplify the APIs to clear them out. I think we can merge this first to the main. If you need more , I will continue to contribute if I have time. Thanks

[Piedone]

@sarahelsaig did you see the updates here?

[sarahelsaig]

I was waiting for some followup from @wAsnk . As things are, I think we can merge this. Any further changes can be done internally within a different issue. It will be okay as long as it happens before the next release.