Add VIM emulation
GtkSourceView is getting a Vim emulation mode which should be considered an accessibility feature in that for people who traditionally use Vim, using a GtkTextView is an incredibly frustrating experience.
It would be nice to enable this in GNOME Text Editor but I don't want to clutter the preferences. However, if we only toggle it as a GSetting, then enabling it with a flatpak would require editing a config file.
I'm looking for some design input on how/where this should get enabled.
Anyway, having this in Text Editor would help us shake out bugs and also ensure we land something really stable for both Text Editor and Builder on GTK 4.