Support variables in Choose Labels macro#5

In SR4C on-prem the user is able to include some variables (listed below) as labels. We should support these on the cloud as well.

Variables to support:

• $username - Username of the person who created and/or edited the page.
• $fullname - The full name of the person who created and/or edited the page.
• $year - The year when the page was created and/or edited.
• $month - The month when the page was created and/or edited.
• $day - The day when the page was created and/or edited.
• $parent - The parent title of the current page.