DMN editor: 7.6 Search - UX discovery/research

Follow-up to https://issues.jboss.org/browse/DROOLS-4142, to extend the Find feature to search across the entire DMN file/tabs within the editor.

This story is to gather use cases, requirements and acceptance criteria as defined at: https://www.yodiz.com/blog/user-stories-acceptance-definition-and-criteria-in-agile-methodologies/

Verification conditions: Documented use case and acceptance criteria for this feature, particularly as it relates to user experience and design.