'readonly' Common Field Property

User Story

As a Form Designer, I want to specify which elements of a form defined using Form Language are read only, so the form renderer can display the data appropriately, and not allow user data entry.

Acceptance Criteria

1. In the Form Model describing the form, I can set a 'readonly' = true property on any form data element. The default is 'readonly' = false.
2. When the form is rendered based on the Form Model, the data is displayed appropriately (e.g., text/classifier values/dates/times as read only labels, booleans/tri-state as disabled checkboxes, etc.) and does not allow user data entry.