Refactor the license check to be a generic presubmit check (#131)

* Refactor the license check to be a generic presubmit check

This includes all of the old presubmits that were in our METADATA file
that are still valid.

* Responses to CR

Added docstrings, refactored the file finder, changed variable names,
and formatted the file

* More respones to CR

core/src/main/java/google/registry/bigquery/BigqueryConnection.java

@@ -727,7 +727,7 @@ public class BigqueryConnection implements AutoCloseable {
               .setProjectId(getProjectId())
               .setDatasetId(datasetName)))
           .execute();
-      System.err.printf("Created dataset: %s:%s\n", getProjectId(), datasetName);
+      logger.atInfo().log("Created dataset: %s:%s\n", getProjectId(), datasetName);
       return true;
     }
     return false;