Change default to enable @DbArray as nullable and @Transient initialisation

This changes the default behavior for ebean version 13.12.0 or greater to:

Allow nullable @DbArray
Initialise @Transient fields when ebean-agent generates a default constructor
Errors when ebean-agent is unable to initialise @Transient fields in a generated default constructor

To disable these features add a src/main/resources/ebean.mf with these features turned off:

allow-nullable-dbarray: false
transient-init: false
transient-init-error: false

ebean-orm / ebean-agent