Need Test Case for updating @READONLY fields using redcapAPI

[sharpwb]

We need a test case in the R redcapAPI project that will expose when a field with an annotation of:

@readonly annotation

@READONLY-APP annotation

@READONLY-FORM annotation

@READONLY-SURVEY annotation

Cannot be written to via the API.

Linked to this issue in Jira
https://jira.app.vumc.org/browse/BSTATGEN-1176