feat(json-api-context): store a list of relationships to update

when PATCHing entities, we need to know which relationships to also PATCH

Author: jaredcnance

src/JsonApiDotNetCore/Services/IJsonApiContext.cs

@@ -3,6 +3,7 @@
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Internal.Query;
+using JsonApiDotNetCore.Models;
 
 namespace JsonApiDotNetCore.Services
 {
@@ -20,5 +21,6 @@ public interface IJsonApiContext
         PageManager PageManager { get; set; }
         IMetaBuilder MetaBuilder { get; set; }
         IGenericProcessorFactory GenericProcessorFactory { get; set; }
+        Dictionary<RelationshipAttribute, object> RelationshipsToUpdate { get; set; }
     }
 }

src/JsonApiDotNetCore/Services/JsonApiContext.cs

@@ -4,6 +4,7 @@
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Internal;
 using JsonApiDotNetCore.Internal.Query;
+using JsonApiDotNetCore.Models;
 using Microsoft.AspNetCore.Http;
 
 namespace JsonApiDotNetCore.Services
@@ -23,6 +24,7 @@ public JsonApiContext(
             Options = options;
             MetaBuilder = metaBuilder;
             GenericProcessorFactory = genericProcessorFactory;
+            RelationshipsToUpdate = new Dictionary<RelationshipAttribute, object>();
         }
 
         public JsonApiOptions Options { get; set; }
@@ -36,6 +38,7 @@ public JsonApiContext(
         public PageManager PageManager { get; set; }
         public IMetaBuilder MetaBuilder { get; set; }
         public IGenericProcessorFactory GenericProcessorFactory { get; set; }
+        public Dictionary<RelationshipAttribute, object> RelationshipsToUpdate { get; set; }
 
         public IJsonApiContext ApplyContext<T>()
         {