Migrate Commons Lang from 2 to 3 and StringEscapeUtils to Commons Text (#401)

Co-authored-by: Bruno Verachten <gounthar@users.noreply.github.com>

Author: gounthar

rest-api/pom.xml

@@ -46,6 +46,10 @@
     </scm>
 
     <dependencies>
+    <dependency>
+      <groupId>io.jenkins.plugins</groupId>
+      <artifactId>commons-lang3-api</artifactId>
+    </dependency>
         <dependency>
             <groupId>org.jenkins-ci.plugins.workflow</groupId>
             <artifactId>workflow-api</artifactId>

rest-api/src/main/java/com/cloudbees/workflow/rest/external/ChangeSetExt.java

@@ -27,7 +27,7 @@
 import com.fasterxml.jackson.annotation.JsonInclude;
 import hudson.scm.ChangeLogSet;
 import hudson.scm.RepositoryBrowser;
-import org.apache.commons.lang.StringUtils;
+import org.apache.commons.lang3.StringUtils;
 import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 
 import java.io.IOException;