Add support for date type when editing properties in agreement settings

Purpose:
Support for setting a agreement custom property to have type 'date' in the agreement settings

User story statement(s):

As an ERM librarian
I want to add a new agreement property with type = date
so that I can record properties that are expressed as dates

Scenarios:

1. Scenario:
   • Given the agreement settings -> properties
   • When I add a new property and click the 'type' dropdown
   • Then I see the option to use 'date'
2. Scenario:
   • Given I have selected 'date' as the property type
   • When I save the property
   • Then it has a type of date