Improve Screen Variables Manager

Issue & Reproduction Steps

Expected behavior:

Actual behavior:

Test the steps above

[ ] I have pulled this code locally and tested it on my instance, along with any associated packages.
[ ] This code adheres to ProcessMaker Coding Guidelines.
[ ] This code includes a unit test or an E2E test that tests its functionality, or is covered by an existing test.
[ ] This solution fixes the bug reported in the original ticket.
[ ] This solution does not alter the expected output of a component in a way that would break existing Processes.
[ ] This solution does not implement any breaking changes that would invalidate documentation or cause existing Processes to fail.
[ ] This solution has been tested with enterprise packages that rely on its functionality and does not introduce bugs in those packages.
[ ] This code does not duplicate functionality that already exists in the framework or in ProcessMaker.
[ ] This ticket conforms to the PRD associated with this part of ProcessMaker.