Implemented a new test class covering copy and paste functionality for
resources in the Common Navigator-based Project Explorer.

Key tests include:
- Verify Copy/Paste/Delete actions exist in context menu for resources
- Copy enablement for single resource selection
- Copy-to-clipboard verification using ResourceTransfer and TextTransfer
- Paste enablement based on clipboard contents and target selection
- End-to-end copy-paste round-trip between different projects

These tests ensure EditActionGroup and its constituent CopyAction and
PasteAction are correctly wired and functional.