Construct a GroovyCodeSource for an inputStream of groovyCode that has an
unknown provenance -- meaning it didn't come from a File or a URL (e.g. a String).
The supplied codeBase will be used to construct a File URL that should match up
with a java Policy entry that determines the grants to be associated with the
class that will be built from the InputStream.
The permission groovy.security.GroovyCodeSourcePermission will be used to determine if the given codeBase
may be specified. That is, the current Policy set must have a GroovyCodeSourcePermission that implies
the codeBase, or an exception will be thrown. This is to prevent callers from hijacking
existing codeBase policy entries unless explicitly authorized by the user.