Update ThanksTo in the AboutDlg

Update ThanksTo in the AboutDlg

This was pretty outdated and mentioned companies that no longer exist.
Bring the content of that tab into the present. Add new icons, remove
old.

Also modernize the code a tiny bit, and ease the life of translators
by factoring out most of the RichText stuff.

(cherry picked from commit 69e767d13b6c2880a46d8a84cfab6678b15b26cf)

Conflicts:
    src/qtui/aboutdlg.cpp