[TASK] CGL cleanups in Iterator / Extract ViewHelper
[TASK] Remove glue capability from Iterator / Extract ViewHelper

This particular operation, along with any other advanced array post processing, is handled by chaining other v:iterator ViewHelpers.
[TASK] Improve error handling in Iterator / Extract ViewHelper
[DOC] Made doc comment for Iterator / Extract ViewHelper markdown format
[TASK] Adjust UnitTests to code changes

Removes the glue parameter that is provided by another ViewHelper and
changes the parameter order to fit the new method signature.