Finds the previous actionRg, generated by a previous addAnimation.
If it exists, it links to the previous actionRg to a newly created actionRg,
If doesn't exist just creates a actionRg.
_findActionRg uses elementAdpt.getProp('uid', args) to determine if has already
an ActionRg.
Finds the previous
actionRg, generated by a previousaddAnimation. If it exists, it links to the previousactionRgto a newly createdactionRg, If doesn't exist just creates aactionRg._findActionRguseselementAdpt.getProp('uid', args)to determine if has already an ActionRg.