Add support for default Zip Code

[respencer]

Description & Issue number it closes

Adds support for a default Zip Code.

Resolves #6951

Screenshots (if appropriate)

How to test the changes?

• Check that the field is in /SystemSettings.php#PeopleSetup
• Typed in a value & save
• Go to /FamilyEditor.php & confirm that the field is pre-populated.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Visual inspection.
• Check that the field was in /SystemSettings.php
• Typed in a value & saved
• Checked that the value was saved in the DB.
• Went to /FamilyEditor.php & confirmed that the field was pre-populated.

Changes applied and tested on live site.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[DawoudIO]

Please note that you have to regen the locale files when you add new strings

[DawoudIO]

tested and works
thank you