Handle subgraph schema entity array type and relation fields (#49)

* Handle relation entities in subgraph

* Modify eden-watcher entities to handle subgraph schema data types

* Modify schema gql to match eden subgraph gql shape

* Handle array type fields in subgraph schema

* Fix store get api for array type fields in subgraph entities

* Handle array type in eden-watcher and format await used in params

packages/graph-node/test/subgraph/example1/schema.graphql

@@ -3,6 +3,13 @@ enum EnumType {
   choice2
 }
 
+type RelatedEntity @entity {
+  id: ID!
+  paramBigInt: BigInt!
+  examples: [ExampleEntity!]!
+  bigIntArray: [BigInt!]!
+}
+
 type ExampleEntity @entity {
   id: ID!
   count: BigInt!
@@ -12,4 +19,5 @@ type ExampleEntity @entity {
   paramBytes: Bytes!
   paramEnum: EnumType!
   paramBigDecimal: BigDecimal!
+  related: RelatedEntity!
 }