feat: typescript typings (#9)

* add graphqlas a dev dependency and peer dependency for having the TypeScript typings available.

* add typescript typings for the exported modules.

* feat: Remove the graphql-js dependency and use generics instead.

package.json

@@ -3,6 +3,7 @@
   "version": "2.1.0",
   "description": "Cross browser function to fetch and parse streaming multipart graphql responses.",
   "main": "dist/index.js",
+  "types": "./typings.d.ts",
   "repository": "[email protected]:relay-tools/fetch-multipart-graphql.git",
   "author": "Rob Richard <[email protected]>",
   "license": "MIT",

typings.d.ts

@@ -0,0 +1,22 @@
+// Minimum TypeScript Version: 3.0
+
+declare class PatchResolver<T = unknown> {
+    constructor(params?: { 
+        onResponse: (result: T[]) => void
+        boundary?: string;
+    })
+}
+
+declare function MultipartFetchFunction<T = unknown>(url: string, params: {
+    method?: string;
+    headers?: Record<string, string>;
+    credentials?: string;
+    body?: string;
+    onNext: (result: T[]) => void;
+    onError: (error: unknown) => void;
+    onComplete : () => void
+}): void
+
+
+export { PatchResolver}
+export default MultipartFetchFunction