Make keyboard activation of OK save settings instead of cancelling.
Also, fix the string for the shortcut so that it works (shortcut
unchanged).
Fixes: https://gitlab.com/kicad/code/kicad/-/issues/13303
Options that do not have code implementing them are now hidden from the
user so that they are not searching for ways to enable the greyed out
options. Similarly, when selecting a routing option that disables
free-mode, we show the effect of disabling the mode in the dialog.