Add cloudbees-folder to test scope

[basil]

While running Plugin Compatibility Tester (PCT) against this plugin I noticed the following failure:

java.lang.ClassNotFoundException: com.cloudbees.hudson.plugins.folder.AbstractFolder
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
Caused: java.lang.NoClassDefFoundError: com/cloudbees/hudson/plugins/folder/AbstractFolder
	at org.jenkinsci.plugins.configfiles.ConfigFiles.getByIdOrNull(ConfigFiles.java:139)
	at org.jenkinsci.plugins.configfiles.ConfigFiles.getByIdOrNull(ConfigFiles.java:169)
	at org.jenkinsci.lib.configprovider.model.ConfigFileManager.provisionConfigFile(ConfigFileManager.java:67)
	at jenkins.plugins.nodejs.NodeJSCommandInterpreter.perform(NodeJSCommandInterpreter.java:172)
	at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:92)
	at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
	at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:818)
	at hudson.model.Build$BuildExecution.build(Build.java:199)
	at hudson.model.Build$BuildExecution.doRun(Build.java:164)
	at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:526)
	at hudson.model.Run.execute(Run.java:1895)
	at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:44)
	at hudson.model.ResourceController.execute(ResourceController.java:101)
	at hudson.model.Executor.run(Executor.java:442)

This PR chases away the failure by adding cloudbees-folder (of a BOM managed version) to test scope.

Testing done

Successfully ran PCT with this change on Java 21. Before this change, I got:

[ERROR] Errors: 
[ERROR]   JCasCTest>RoundTripAbstractTest.lambda$roundTripTest$0:104->assertConfiguredAsExpected:64->checkConfigFile:69 » NoClassDefFound com/cloudbees/hudson/plugins/folder/AbstractFolder
[ERROR]   NpmrcFileSupplyTest.test_supply_npmrc_with_registry:67 » NoClassDefFound com/cloudbees/hudson/plugins/folder/AbstractFolder

[basil]

Currently blocking jenkinsci/bom#2437

[MarkEWaite]

Thanks!

[MarkEWaite]

Thanks for merging @nfalco79 ! Looking forward to a release so that this plugin can be included in the bill of materials.

[basil]

Looking forward to a release so that this plugin can be included in the bill of materials.

I am looking forward to it, too!