Create fieldset/form validators and export

[geniuspacs]

We realized that validator FormElementHasNoError is not exported and has no message, and this means that anyone who want to print a validation message when a fieldset or a form has any error can´t do it.

Out proposal is create a kind of validators for fieldset or forms and export it. This means export this validator and also create more, for example when a fieldset or form have warnings, info, etc...

Do you guys thinks this could be a good idea?