added r2 binding support to cf adapter

app/src/adapter/cloudflare/bindings.ts

@@ -0,0 +1,32 @@
+export type BindingTypeMap = {
+   D1Database: D1Database;
+   KVNamespace: KVNamespace;
+   DurableObjectNamespace: DurableObjectNamespace;
+   R2Bucket: R2Bucket;
+};
+
+export type GetBindingType = keyof BindingTypeMap;
+export type BindingMap<T extends GetBindingType> = { key: string; value: BindingTypeMap[T] };
+
+export function getBindings<T extends GetBindingType>(env: any, type: T): BindingMap<T>[] {
+   const bindings: BindingMap<T>[] = [];
+   for (const key in env) {
+      try {
+         if (env[key] && (env[key] as any).constructor.name === type) {
+            bindings.push({
+               key,
+               value: env[key] as BindingTypeMap[T]
+            });
+         }
+      } catch (e) {}
+   }
+   return bindings;
+}
+
+export function getBinding<T extends GetBindingType>(env: any, type: T): BindingMap<T> {
+   const bindings = getBindings(env, type);
+   if (bindings.length === 0) {
+      throw new Error(`No ${type} found in bindings`);
+   }
+   return bindings[0] as BindingMap<T>;
+}