Issue #3520847: Prevent empty table cells for form elements of type 'hidden' or 'value'

Closes #3520847

Proposed solution

Update Table.php to skip rendering td tag cells for hidden/value elements, while still preserving table structure.
Added a kernel test to verify that hidden/value elements no longer produce empty table cells.

Files changed

• core/lib/Drupal/Core/Render/Element/Table.php
• core/tests/Drupal/KernelTests/Core/Render/Element/TableTest.php