Fix Table Selection polluting clipboard history

The Table Select tool no longer automatically copies its
contents to the clipboard, but only to the selection clipboard.
(Middle-click paste clipboard.) Instead, after creating
the table, the user can right-click to bring up a popup
menu with the action "Copy Table Contents to the Clipboard".
Clicking on this will copy the table contents to the clipboard.
Ctrl+C also works.

BUG: 402110