A Supplier that returns an instance of a ClassLoader to be used
for loading Java classes into the currently-running script.
The Supplier should return a new instance for every invocation of this method
if it is desired that classes loaded by any one invocation of the
"trireme-support" module's "loadJars" method are isolated from classes loaded
from another invocation of the "loadJars" method.
The Supplier may return the same instance for every invocation of this method
if such isolation is not desired.