files-clients-114: missing copyright headers

Signed-off-by: daniele-verducci <daniele.verducci@nextcloud.com>

Author: daniele-verducci

app/src/main/res/drawable/ic_add_more_documents.xml

@@ -1,18 +1,8 @@
 <!--
-  ~ Copyright (C) 2026 The Android Open Source Project
-  ~
-  ~ 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.
-  -->
+  ~ SPDX-FileCopyrightText: 2026 Daniele Verducci <daniele.verducci@nextcloud.com>
+  ~ SPDX-FileCopyrightText: 2018-2026 Google LLC
+  ~ SPDX-License-Identifier: Apache-2.0
+-->
 <vector xmlns:android="http://schemas.android.com/apk/res/android" android:autoMirrored="true" android:height="24dp" android:tint="#000000" android:viewportHeight="24" android:viewportWidth="24" android:width="24dp">
 
     <path android:fillColor="@android:color/white" android:pathData="M13,11h-2v3L8,14v2h3v3h2v-3h3v-2h-3zM14,2L6,2c-1.1,0 -2,0.9 -2,2v16c0,1.1 0.89,2 1.99,2L18,22c1.1,0 2,-0.9 2,-2L20,8l-6,-6zM18,20L6,20L6,4h7v5h5v11z"/>

app/src/main/res/drawable/ic_nav_back.xml

@@ -1,3 +1,8 @@
+<!--
+  ~ SPDX-FileCopyrightText: 2026 Daniele Verducci <daniele.verducci@nextcloud.com>
+  ~ SPDX-FileCopyrightText: 2018-2026 Google LLC
+  ~ SPDX-License-Identifier: Apache-2.0
+-->
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
     android:width="24dp"
     android:height="24dp"

app/src/main/res/drawable/ic_nav_forward.xml

@@ -1,3 +1,8 @@
+<!--
+  ~ SPDX-FileCopyrightText: 2026 Daniele Verducci <daniele.verducci@nextcloud.com>
+  ~ SPDX-FileCopyrightText: 2018-2026 Google LLC
+  ~ SPDX-License-Identifier: Apache-2.0
+-->
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
     android:width="24dp"
     android:height="24dp"