Show error in form when a title is duplicated.

    <br>* LocalStorage and LocalListCache updated with some fixes surrounding objects replacing current data with stale data<br>* Exception for duplicate titles and codes/slugs is more descriptive<br>* mixin created for unique title enforcement, using can/map/validations<br>* Added support for suppressing errors in computed_errors compute -- useful for not showing validation errors immediately when spawning a new object form.<br>* Error suppression turns off as soon as the user starts interacting with the form<br>* A migration that enforces uniqueness for titles on some tables -- if duplicates already exist they have the object ID appended in parentheses<br><br>Ref p/69962294 b/13886201