[JENKINS-60619] Java 11 compatibility

[mat1e]

JENKINS-60619

Boon library used by the plugin to parse JSON is not compatible with JDK 11.
This PR remove Boon library from the plugin and use groovy.json.* parser.

In your script you don't have to call Boon library anymore :

Before :

import org.boon.Boon;

def jsonEditorOptions = Boon.fromJson(/{...}/);

After :

def jsonEditorOptions = new groovy.json.JsonSlurper().parseText(/{...}/);

[mat1e]

@vimil,
Is it possible to make a new release of the plugin to integrate this fix ?
Actually, we are building the plugin ourself, but we prefers to install it with jenkins plugin managment as usual...

Also, we can close JENKINS-60619 after the release ;)

[luorigufeng]

Could you update the help manual?
https://plugins.jenkins.io/extended-choice-parameter/