CICD: Update the android Build Docker Image.

Update the android build docker image:
- rebase on ubuntu 22.04;
- add tooling required to sign APKs;
- changes to make the container re-usable;
- change to a multi-stage build to keep the image size smaller;
- generic improvements to the Dockerfile

Also update the example script for how to use the container.

Signed-off-by: Michael Keller <github@ike.ch>

scripts/docker/android-build-container/setup-docker.sh

@@ -5,16 +5,16 @@
 # Google makes it intentionally very hard to download the command line tools
 # the URL is constantly changing and the website requires you to click through
 # a license.
+#
 # Today this URL works:
-if [ ! -f commandlinetools-linux-6858069_latest.zip ] ; then
-	wget https://dl.google.com/android/repository/commandlinetools-linux-6858069_latest.zip
-fi
-# if this fails, go to https://developer.android.com/studio#cmdline-tools and click through
-# for yourself...
+# https://dl.google.com/android/repository/commandlinetools-linux-6858069_latest.zip
+#
+# If this fails, go to https://developer.android.com/studio#cmdline-tools and
+# click through for yourself, and then update the URL in the Dockerfile
 
 # copy the dependency script into this folder
 cp ../../../packaging/android/android-build-setup.sh .
 cp ../../../packaging/android/variables.sh .
 
 # create the container (this takes a while)
-sudo docker build -t android-builder --squash .
+docker build -t android-build .