Added unsetValueOption() to the Form\Element\Select and Form\Element\MultiCheckbox
Updated Form\Element\Select & MultiCheckbox, fixed unsetValueOption() @return self
Merge pull request #5562 from bacinsky/feature/select_and_multicheckbox_unset_value_option

Add unsetValueOption() to the Form\Element\Select and Form\Element\MultiCheckbox
Merge branch 'feature/5562' into develop

Close #5562