chore: add MPL license headers to all source files (#2977)

src/app/shared/language-selector/language-selector.component.html

@@ -1,3 +1,10 @@
+<!--
+  Copyright since 2025 Mifos Initiative
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+-->
 <mat-form-field id="language-selector" [appearance]="appearance" [class.outlined-variant]="appearance === 'outline'">
   @if (showLabel) {
     <mat-label>{{ 'labels.inputs.Language' | translate }}</mat-label>