Make kotlin-android-extensions always cause a compilation error.

kotlin-android-extensions are deprecated and have been scheduled
for removal in 1.8.0.

https://android-developers.googleblog.com/2022/02/discontinuing-kotlin-synthetics-for-views.html

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/android/internal/AndroidSubplugin.kt

@@ -36,8 +36,8 @@ class AndroidExtensionsSubpluginIndicator @Inject internal constructor(private v
         registry.register(KotlinAndroidExtensionModelBuilder())
         project.plugins.apply(AndroidSubplugin::class.java)
 
-        project.logger.warn(
-            "Warning: The 'kotlin-android-extensions' Gradle plugin is deprecated. " +
+        project.logger.error(
+            "Error: The 'kotlin-android-extensions' Gradle plugin is no longer supported. " +
                     "Please use this migration guide (https://goo.gle/kotlin-android-extensions-deprecation) to start " +
                     "working with View Binding (https://developer.android.com/topic/libraries/view-binding) " +
                     "and the 'kotlin-parcelize' plugin."