Cleanup and Modernize webbrowser

[DBJim]

Feature or enhancement

Certain browsers supported by webbrowser are now completely obsolete (and in some cases, have been for over 20 years).

I suggest to remove support for historical browsers from webbrowser, as they aren't used today, and it leaves us with a simpler and more modern module.

Pitch

Propose to remove the following:

-Mosaic - Final release in 1997
-Grail - Final release in 1999
-Netscape - Final release in 2008
-Galeon - Final release in 2008
-SkipStone - Final release in 2012
-Iceape - Development ended 2013
-Old Firefox versions 35 and below (2014)
-related tests which do not work for modern Firefox

Other improvements:

Add "Chrome" to the PATH lookup performed on Windows when user hasn't set a default browser
Add commentary for the symbolic links checked on Linux.
Rename Galeon class to Epiphany.
Update dead links.

Previous discussion

#86496
#67451
#87303
#102690

Any feedback or suggestions welcome!

Linked PRs

• gh-102871: Remove obsolete browsers from webbrowser #102872

[DBJim]

Added SkipStone to the list, originally added in 2005. I can find no evidence of modern usage.