[v6] Implement Realtime Database (#2195)

* [database] recreate database branch based off of #2185

* [database] cleanup linting issues

* [database] enable tests

* [database] add to tests deps

packages/database/e2e/DatabaseStatics.e2e.js

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+describe('database.X', () => {
+  describe('ServerValue.TIMESTAMP', () => {
+    it('returns a valid object', () => {
+      const { TIMESTAMP } = firebase.database.ServerValue;
+      should.equal(Object.keys(TIMESTAMP).length, 1);
+      TIMESTAMP.should.have.property('.sv');
+      TIMESTAMP['.sv'].should.eql('timestamp');
+    });
+  });
+});