SUMMARY
Make translation units searchable by metadata/file reference.

Use case:
Filter all messages in www_www.po that come from file plasma-5.17.0.php.
For now these can be found with Pology, but not using just Lokalize tools:
  posieve find-messages -sntransl -scomment:'plasma-5.17.0.php' www_www.po

I see two approaches to fulfill the use case:
 1. Add column "unit metadata" in the Translation Units panel and make it searchable.
 2. Organize messages in the Translation Units panel in a tree view where top-level nodes represent source file references. Would be similar to how Qt Linguist works. I know there will be duplicate messages across different files, we can just display them multiple times in the tree view.

Example:

  + dolphincontextmenu.cpp
     . "Empty Trash"
     . "Restore"
     . "Create New"
  + panels/places/placespanel.cpp
     . "Empty Trash"
     . "Show Hidden Places"

STEPS TO REPRODUCE
1. 
2. 
3. 

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION