androiddeployqt: Add a placeholder for plugin type in build.gradle

This allows to later change the plugin type based on the options
provided for the androiddeployqt, such as when building an AAR.

Task-number: QTBUG-116955
Task-number: QTBUG-65567
Change-Id: I6314c8ab9edccbf953ae48543d5a002a9f807581
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

src/android/templates/build.gradle

@@ -14,7 +14,7 @@ repositories {
     mavenCentral()
 }
 
-apply plugin: 'com.android.application'
+apply plugin: qtGradlePluginType
 
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar'])
@@ -29,6 +29,7 @@ android {
      * - qtAndroidDir - holds the path to qt android files
      *                   needed to build any Qt application
      *                   on Android.
+     * - qtGradlePluginType - whether to build an app or a library
      *
      * are defined in gradle.properties file. This file is
      * updated by QtCreator and androiddeployqt tools.

src/tools/androiddeployqt/main.cpp

@@ -2850,6 +2850,7 @@ bool buildAndroidProject(const Options &options)
         abiList.append(it.key());
     }
     gradleProperties["qtTargetAbiList"] = abiList.toLocal8Bit();// armeabi-v7a or arm64-v8a or ...
+    gradleProperties["qtGradlePluginType"] = "com.android.application";
     if (!mergeGradleProperties(gradlePropertiesPath, gradleProperties))
         return false;