ci: enable gh annotations with ast-grep (#14840)

Error is still printed to console, but in a special structured format
recognized by actions to highlight and annotate the problem in your PR.

When clicking the build failure, annotations can be seen at the very top
of action link (no need to look at logs). Github does highlight the
failures in red in the logs as well.

You can see the problems annotated inline in the sources, when reviewing
the changes.

Author: rmuir

build-tools/build-infra/src/main/java/org/apache/lucene/gradle/plugins/astgrep/AstGrepPlugin.java

@@ -17,6 +17,7 @@
 package org.apache.lucene.gradle.plugins.astgrep;
 
 import com.carrotsearch.gradle.buildinfra.buildoptions.BuildOptionsExtension;
+import java.util.ArrayList;
 import java.util.List;
 import org.gradle.api.GradleException;
 import org.gradle.api.Plugin;
@@ -67,9 +68,15 @@ public void apply(Project project) {
                         optionName);
               }
 
+              var args = new ArrayList<String>();
               // fail on any rule match regardless of severity level
-              task.setArgs(
+              args.addAll(
                   List.of("scan", "-c", "gradle/validation/ast-grep/sgconfig.yml", "--error"));
+              // use the github format when being run as a workflow
+              if (System.getenv("CI") != null && System.getenv("GITHUB_WORKFLOW") != null) {
+                args.addAll(List.of("--format", "github"));
+              }
+              task.setArgs(args);
             });
 
     // Common configuration.