FR: Add "Display CopyQ Version" as a menuitem in the Help menu

**Is your feature request related to a problem? Please describe.**
When reporting bugs, it is most useful if people include the info from the `copyq version` command.

**Describe the solution you'd like**
Add "Display CopyQ Version..." as a menuitem in the Help menu that pops open a little window with the results of the `copyq version` command. That window can have a button to copy the text to the clipboard.

**Describe alternatives you've considered**
Mind meld with Lukas to transfer version data details. :)

**Additional context**
This will also help relive congestion in the `Item` menu, since those of us who report bugs likely have `copyq version` in that menu.