Revert "Revert "Merge pull request #42 from gpsantos/GRAILS-11670""

This reverts commit 2b29b657cb4a35337410c4b52ca0661a14eb24b3.
GRAILS-11670 - Creating TestGormEnhancer and TestCriteriaBuilder to be used for tests and implement readOnly() as no-op.
Merge pull request #45 from gpsantos/GRAILS-11670

Grails 11670 - Adding support for readOnly operation on unit tests