Fix copy of srcaar to aar files when using mainGradle.template.

After modifing PluginImporter settings, assets need to be reimported
for the changes to be applied in some versions of Unity.

Reported in firebase/quickstart-unity#377

Bug: 135125825

Change-Id: I6ca17391d3f89f213a8a21bea6613d3321ed7386

Author: Stewart Miles

source/PlayServicesResolver/src/GradleTemplateResolver.cs

@@ -129,6 +129,10 @@ private static bool CopySrcAars(ICollection<Dependency> dependencies) {
                     }
                     if (configuredAar) {
                         aarFiles.Add(targetFilename);
+                        // Some versions of Unity do not mark the asset database as dirty when
+                        // plugin importer settings change so reimport the asset to synchronize
+                        // the state.
+                        AssetDatabase.ImportAsset(targetFilename, ImportAssetOptions.ForceUpdate);
                     } else {
                         if (File.Exists(targetFilename)) {
                             AssetDatabase.DeleteAsset(targetFilename);