Run precommit checks before checkstyle task (opensearch-project#3727)

### Description

This PR runs the License Header check with the checkstyle CI check to
ensure that PRs contain licenses on top of new files. This PR also adds
the license on 2 files where its missing today.

* Category (Enhancement, New feature, Bug fix, Test fix, Refactoring,
Maintenance, Documentation)

Maintenance

### Issues Resolved

- Resolves opensearch-project#3471
- Resolves opensearch-project#3691

### Check List
- [ ] New functionality includes testing
- [ ] New functionality has been documented
- [ ] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and
signing off your commits, please check
[here](https://github.com/opensearch-project/OpenSearch/blob/main/CONTRIBUTING.md#developer-certificate-of-origin).

---------

Signed-off-by: Craig Perkins <[email protected]>

build.gradle

@@ -386,6 +386,7 @@ checkstyle {
 }
 
 tasks.withType(Checkstyle) {
+ dependsOn(':precommit')
  reports {
  ignoreFailures = false
  }

src/main/java/org/opensearch/security/filter/NettyAttribute.java

@@ -1,3 +1,13 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+ */
+
 package org.opensearch.security.filter;
 
 import java.util.Optional;

src/main/java/org/opensearch/security/filter/SecurityResponse.java

@@ -36,7 +36,6 @@ public class SecurityResponse {
 
  public SecurityResponse(final int status, final Exception e) {
  this.status = status;
- populateHeaders(CONTENT_TYPE_APP_JSON);
  this.body = generateFailureMessage(e);
  this.contentType = XContentType.JSON.mediaType();
  }

src/test/java/org/opensearch/security/filter/SecurityRestUtilsTests.java

@@ -1,3 +1,13 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+ */
+
 package org.opensearch.security.filter;
 
 import org.junit.Test;