Add option to enable public groups on the webform

[jitendrapurohit]

Overview

Resubmission of #640 with test.

Before

https://chat.civicrm.org/civicrm/pl/u9pouzzjcidmbmf3dnmmcuwfsw

iirc for Webform - currently we have the Groups field we can set to 'user select' but that then puts all groups on show, and one has to manually untick all non-public ones if the goal is to have this field function as a newsletter sign up group - correct? if so, do others see the benefit in having an option in the setting dropdown for eg
user selects (all groups)
user selects (public groups only)
and then hopefully that list would change on the form dynamically as Public Groups were added/removed. thoughts?

After

Group field has a new option

If chosen - only public groups (visibility = public pages) will be loaded on the webform element.

Comments

Drupal Ticket = https://www.drupal.org/project/webform_civicrm/issues/3303795