fix(graphql): support nested arrays when generating type defs

Author: kamilmysliwiec

packages/apollo/tests/generated-definitions/array-property.fixture.ts

@@ -12,6 +12,9 @@ export interface Foo {
     b?: Nullable<string[]>;
     c: Nullable<string>[];
     d?: Nullable<Nullable<string>[]>;
+    e: string[][];
+    f: string[][][];
+    g?: Nullable<Nullable<Nullable<Nullable<string>[]>[]>[]>;
 }
 
 type Nullable<T> = T | null;

packages/apollo/tests/generated-definitions/array-property.graphql

@@ -3,4 +3,7 @@ type Foo {
   b: [String!]
   c: [String]!
   d: [String]
+  e: [[String!]!]!
+  f: [[[String!]!]!]!
+  g: [[[String]]]
 }