[types][database] rework types

packages/database/type-test.ts

@@ -0,0 +1,36 @@
+import firebase from '@react-native-firebase/app';
+import defaultExport, { firebase as firebaseFromModule } from '@react-native-firebase/database';
+
+// checks module exists at root
+console.log(firebase.database().app.name);
+console.log(firebase.database().ref('foo/bar'));
+
+// checks module exists at app level
+console.log(firebase.app().database().app.name);
+console.log(
+  firebase
+    .app()
+    .database()
+    .ref('foo/bar'),
+);
+
+// check module accepts a string arg
+console.log(firebase.app().database('some-string').app.name);
+
+// checks statics exist
+console.log(firebase.database.SDK_VERSION);
+
+// checks statics exist on defaultExport
+console.log(defaultExport.SDK_VERSION);
+
+// checks root exists
+console.log(firebase.SDK_VERSION);
+
+// checks firebase named export exists on module
+console.log(firebaseFromModule.SDK_VERSION);
+
+// checks multi-app support exists
+console.log(firebase.database(firebase.app()).app.name);
+
+// checks default export supports app arg
+console.log(defaultExport(firebase.app()).app.name);