App Center Integration with CI/CD workflow (#644)

Add Ionia client id to secrets
Update how to build android instructions
Change devicelocale version as it caused issues when building
Add trigger for send test build to transfer.sh and notify slack channel

tool/utils/secret_key.dart

@@ -28,6 +28,7 @@ class SecretKey {
     SecretKey('simpleSwapApiKey', () => ''),
     SecretKey('anypayToken', () => ''),
     SecretKey('onramperApiKey', () => ''),
+    SecretKey('ioniaClientId', () => ''),
   ];
 
   final String name;