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.
Moved Instance and Static API classes to separate files
Added static collection methods to entity classes
Added more cases of returning a transient property
Added new TimeZoneToString converter as default toString method not
getting recreated back to the corresponding timezone
Added new TimeZoneToString converter as default toString method not
getting recreated back to the corresponding timezone.
Stores WriteOptions/QueryOptions per thread per object
Add methods to allow - updates of non collection types on an entity;
individual manipulatation of collection and map types; updates of single
or maps of properties.
Subclassed PendingUpdate classes to store actual statement which can
then be run individually or as part of a batch.
idMap creation refactored to separate method to allow reuse.
property fetchers moved from CassandraQuery to allow reuse.
Cassandra property fetchers moved to CassandraEntityPersister to allow
reuse.
throws exception if findEnum map doesn't contain a string value
Initial addition
Add tests for new entity update static methods
Additional tests for update and deletion of enum properties
Updated to reflect type of exception thrown
test for GRAILS-11787 "hasOne are not initiated as bidirectional (OneToOne)"
fix for GRAILS-11787 "hasOne are not initiated as bidirectional (OneToOne)"
Merge pull request #45 from gpsantos/GRAILS-11670

Grails 11670 - Adding support for readOnly operation on unit tests
GRAILS-11614 Implement use Java delegating metaclass for Groovy proxies
Merge branch 'tomwidmer-feature/GRAILS-11614' into 3.x
add Apache 2 license header to new file
Use CompileStatic in GroovyProxyFactory and access ProxyInstanceMetaClass with static calls