Enable individual readOnly on checkboxes

### Description

Background:
A schema that enables editing data. The schema contains checkboxes that is prefilled based on the existing data. The rules for the schema dictates that the user is not allowed to uncheck a checked checkbox, only check previously unchecked ones. We want the schemas to remain consistent between all versions so all the checkboxes are presented the same.
We would like to be able to individually set readOnly on checkboxes based on logic so that the end user can "see" it and also not be able to uncheck it.
Today we have solved this with validation.

### Additional Information

_No response_

Start by tracing how schema checkboxes are rendered and how checkbox readOnly or validation state is currently handled. Confirm whether readOnly can be set per checkbox from schema logic, then verify that checked read-only boxes remain visible and cannot be unchecked while previously unchecked boxes can still be selected.

Written by the indexing model from the issue text.