keyboard: replace CcAltCharsKeyDialog with a generic XkbModifierDialog
Previously, there were multiple redundant lists of possible values for this setting. This uses one struct to define not only all the possible values, but also anything specific to the alternate characters key, so this can be used for other modifiers. This also changes the style of the dialog to use a GtkListBox.
XkbModifierDialog in 3 minutes and 53 seconds (queued for 5 seconds)7 jobs for