Make GraphType optional

[SimonCropp]

• GraphType is no longer a generic on any methods. instead it is passed as an optional Type parameter.
• to define a default GraphType, register it at startup using GraphTypeTypeRegistry.Register<Company, CompanyGraph>();

[isabekyan]

It seems that something was broken with collection navigation fields in this PR. I get something like
Expected value of type \"Namespace.MyEntityGraph`1[Namespace.Entity]\" for \"Entity\" but got: System.Collections.Generic.HashSet`1[Namespace.Entity]
for any collection field after update...
After update the only change was to replace calls of generic Add...Field to non-generic and passing type of graph param.
Sorry but I had no time to dig into it for more precise info(

[SimonCropp]

Sorry for the hassle. Can u share a minimal repro or a failing unit test?

[isabekyan]

Ooops, my bad.. Haven't noticed that generic AddNavigationField for collections was renamed to non-generic AddNavigationListField.
BTW thanks for this project. Wish I had time to contribute.

[SimonCropp]

@isabekyan happy to accept donations via open collective https://github.com/SimonCropp/GraphQL.EntityFramework#community-backed :)

[isabekyan]

I'm already in )

[SimonCropp]

Sorry should have checked first. Thanks for the support