Add spec and configure codegen

Author: j-piasecki

package.json

@@ -191,5 +191,13 @@
         }
       ]
     ]
+  },
+  "codegenConfig": {
+    "name": "rnasyncstorage",
+    "type": "modules",
+    "jsSrcsDir": "./src",
+    "android": {
+      "javaPackageName": "com.reactnativecommunity.asyncstorage"
+    }
   }
 }

src/NativeAsyncStorageModule.ts

@@ -0,0 +1,26 @@
+import { TurboModuleRegistry, TurboModule } from 'react-native';
+
+export interface Spec extends TurboModule {
+  multiGet: (
+    keys: string[],
+    callback: (error?: Object[], result?: [string, string][]) => void
+  ) => void;
+  multiSet: (
+    kvPairs: [string, string][],
+    callback: (error?: Object[]) => void
+  ) => void;
+  multiRemove: (
+    keys: readonly string[],
+    callback: (error?: Object[]) => void
+  ) => void;
+  multiMerge: (
+    kvPairs: [string, string][],
+    callback: (error?: Object[]) => void
+  ) => void;
+  getAllKeys: (
+    callback: (error?: Object[], result?: [string, string][]) => void
+  ) => void;
+  clear: (callback: (error?: Object[]) => void) => void;
+}
+
+export default TurboModuleRegistry.get<Spec>('RNCAsyncStorage');