Add JSR223 support to given specific jars (ClassLoader)

**orimarko** ([Bug 63538](https://bz.apache.org/bugzilla//show_bug.cgi?id=63538&redirect=false)):
When executing JSR223 script you sometimes need different/older version of jars (as apache commons)

Solution is to add an optional jars folder which will be used as ClassLoader when creating ScriptEngineManager in JSR223BeanInfoSupport

First asked in https://stackoverflow.com/questions/56842003/ways-to-resolve-library-conflict-in-jmeter

Votes in Bugzilla: 1
OS: All

Start by reading JSR223BeanInfoSupport and the surrounding JSR223 script-engine setup. Trace how ScriptEngineManager is created, then determine where an optional jars folder can provide the ClassLoader. Done means scripts can use alternate or older jars when configured, while existing behavior remains unchanged otherwise.

Written by the indexing model from the issue text.