gradle: Suffix ".debug" to package name on debug builds

This will allow us to install debug builds without removing release builds
Signed-off-by: Aayush Gupta <theimpulson@e.email>

app/build.gradle

@@ -21,6 +21,9 @@ android {
     }
 
     buildTypes {
+        debug {
+            applicationIdSuffix ".debug"
+        }
         release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'