Split-browser for Brave browser under f38

Chromium support (which should cover Brave) is still on my to do list, but then again I call my to do list “the append-only ledger”. So it’s probably not going to happen during the lifetime of Fedora 38. More like Fedora 83…

On the bright side, Mullvad Browser works (because as a fork of Tor Browser it is based on Firefox).