JobDSL: add secure Groovy script in sandbox with configure blocks

jobdsl-add-secure-groovy-script-sandbox-with-configure-block.groovy

Closure envVar(String key, String val) {
    return { 
        it / 'buildWrappers' / 'EnvInjectBuildWrapper' / 'info' << {
        	propertiesContent("${key}=${val}")
    	}
    }
}

Closure secureGroovyScript(String scriptText, boolean useSandbox) {
    return {
        it / 'buildWrappers' / 'EnvInjectBuildWrapper' / 'info' << {
            'secureGroovyScript' {
                script(scriptText)
                sandbox(useSandbox)
        	}
    	}
    }
}

freeStyleJob('my-job') {
    wrappers {
        configure secureGroovyScript('println "Hello world!"', true)
        // need to use configure blocks to add more variables to the same
        // configuration, unsure if there is any other way
        configure envVar('BAZ', 'qux')
    }
}