Fix: Speed up build configuration time by lazily verifying apollo-cod…

…egen installation

Move Apollo global verification to the beginning of the task to speed up configuration process.

Before, this I/O operation (version check) would run in configuration time and take up to 5sec. This runs in every Gradle execution (even when unrelated to Apollo)

This commit fixes apollographql#1203 and moves verification to a later stage.

This means that we cannot easily fall-back to local installation that easily. That's why an exception is thrown with an appropriate message. User should disable using this feature if they don't have global installation.

apollo-gradle-plugin/src/main/groovy/com/apollographql/apollo/gradle/ApolloSystemCodegenGenerationTask.groovy

@@ -20,6 +20,9 @@ class ApolloSystemCodegenGenerationTask extends AbstractExecTask<ApolloSystemCod
 
   ApolloSystemCodegenGenerationTask() {
     super(ApolloSystemCodegenGenerationTask.class)
+    doFirst {
+      verifySystemApolloCodegenVersion()
+    }
   }
 
   @Override