github action android build steps

.github/scripts/android/increment-version.ps1

@@ -0,0 +1,12 @@
+$rootPath = $env:GITHUB_WORKSPACE;
+$buildNumber = 3000 + [int]$env:GITHUB_RUN_NUMBER;
+
+$androidManifest = $($rootPath + "\src\Android\Properties\AndroidManifest.xml");
+
+$xml=New-Object XML;
+$xml.Load($androidManifest);
+
+$node=$xml.SelectNodes("/manifest");
+$node.SetAttribute("android:versionCode", [string]$buildNumber);
+
+$xml.Save($androidManifest);