Android: Add a dependency on the AndroidX appcompat library.

It's apache licensed so it's ok, and I need it for some Storage Access
Framework work for #11997.

gradle/wrapper/gradle-wrapper.properties

@@ -4,3 +4,5 @@ distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
 distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-all.zip
+android.useAndroidX=true
+android.enableJetifier=true