Introduce copy icon/functionality to copy a term

As part of the action icons in the second/middle panel of the TermPortal (the one, that lists the terms of an entry) a copy icon should be introduced, that copies the term of the row to the clipboard.

The term of the selected row should be copied with CTRL+C to the clipboard. A tool-tip on the copy icon should show the short-cut. It should also be added to the keyboard-shortcut list in confluence.