copy-on-mouse-select per Pascal Rigaux

On Linux (both Xorg and Wayland), selecting text with mouse or keyboard sends the selected text to PRIMARY selection.

This addon sends mouse selected text to regular clipboard:

> on mouseup, send document.getSelection() to navigator.clipboard.

It is only a 4 lines content_script!


* after install of module, you must reload any existing pages before selecting. Otherwise it will NOT work.
* do not test it on https://addons.mozilla.org/, it will not work


NB: this is mostly https://addons.mozilla.org/fr/firefox/addon/copy-on-select/ with a github a link to see the source code!

NB: it does the same thing as VSCode https://marketplace.visualstudio.com/items?itemName=dinhani.copy-on-select