refactor(corfu): settings and keybinding overhaul

Previously, a distinction was made only between "regular" style (assumed
to be for people who prefer to cycle directionally and commit with RET)
and +tng (assumed to be for people who prefer TAB and auto-commit). This
made composing further variations harder on the user, as they would have
to work around our bindings. Now we have many features as documentation,
and the user can compose to their liking. The global CAPF list was
pruned, suggesting to use individual keys for those functions if
required.

templates/init.example.el

@@ -22,6 +22,7 @@
 
        :completion
        company           ; the ultimate code completion backend
+       ;;(corfu +orderless)  ; complete with cap(f), cape and a flying feather!
        ;;helm              ; the *other* search engine for love and life
        ;;ido               ; the other *other* search engine...
        ;;ivy               ; a search engine for love and life