feat: add one to one relationship for embedding

BREAKING CHANGE: For the cases where one to one relationships are
detected, json objects will be returned instead of json arrays of length
1.

If you wish to override this behavior, you can use computed
relationships to return arrays again.

test/spec/Feature/Query/DeleteSpec.hs

@@ -78,6 +78,32 @@ spec =
           , matchHeaders = ["Content-Range" <:> "*/*"]
           }
 
+      it "embeds an O2O relationship after delete" $ do
+        request methodDelete "/students?id=eq.1&select=name,students_info(address)"
+                [("Prefer", "return=representation")] ""
+          `shouldRespondWith`
+          [json|[
+            {
+              "name": "John Doe",
+              "students_info":{"address":"Street 1"}
+            }
+          ]|]
+          { matchStatus  = 200,
+            matchHeaders = [matchContentTypeJson]
+          }
+        request methodDelete "/students_info?id=eq.1&select=address,students(name)"
+                [("Prefer", "return=representation")] ""
+          `shouldRespondWith`
+          [json|[
+            {
+              "address": "Street 1",
+              "students":{"name": "John Doe"}
+            }
+          ]|]
+          { matchStatus  = 200,
+            matchHeaders = [matchContentTypeJson]
+          }
+
     context "known route, no records matched" $
       it "includes [] body if return=rep" $
         request methodDelete "/items?id=eq.101"