If the user try to save, export or diff a model and it is invalidated,
pgModeler will first validate and then proceed with the pending
operation.

The configuration form was reestrucured decreasing the size occupied on
the screen.
Adde an option on general settings to disable ask to validate model
before save, export and diff.

Minor widgets adjustments
Merge branch 'feat531-inv-model-alert' into model-db-sync