[Swift] Adds a format file and reformats the swift project (#6250)

* Formats files & adds licence

* Revert arrays

* Keeps array indentation as is

* Adds licence to code formatter

* Updates code generators

tests/FlatBuffers.Test.Swift/Sources/SwiftFlatBuffers/main.swift

@@ -1,2 +1,18 @@
+/*
+ * Copyright 2020 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file 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.
+ */
+
 import Foundation
 print("Flatbuffers")