[FR]: Ability to name external tools

[RetroAbstract]

Brief description of the feature request

This feature would allow the user to name an external tool added in "Network & web & tools" > "External tools".

As it is now, when right clicking an article and hovering over "Open with external tool", it's the executable names +".exe" that are listed.

With this feature, if for example I wanted to use Firefox as an external tool, I could name it "Firefox" when adding that external tool to the list, so that when I would click an article and hover over "Open with external tool", RSS Guard would display the name I gave the external tool exe, in this case "Firefox", instead of "firefox.exe".