PR Summary

PR Checklist

[X] [Write Help] Small change to help for extra functionality
[X] [Write Unit Test] No new tests. Fixed some existing tests which need extra files loaded after the change
[X] [Update CHANGELOG.md]

Support selection of WorkItemTypes from a project or from a process-template.
Allow the selection of multiple types using wildcards
Add "hidden" attribute on returned work item types to allow hidden ones to be filtered out later.
Completer no longer suggests hidden (unavailable) WITs
For selection from Process-templates, allow expansion of WIT behaviors, layouts, and/or states
Fixed issue were work item validator was tied to the current project even when adding work items to a different project.