This allows backeds to override a keymap action mapping with lists of mapped hardware inputs instead of just one hardware input id
However, it will still be an overridding, so it will require all hardware input ids for a given keymap action to be added.
In other words, if a backend uses addDefaultBinding() for a given action, it will not ADD to any existing mappings of the action,
other than the ones that the backend itself has added (with addDefaultBinding())
Previously backend defaults where added to the keymap defaults.
However, it became apparent backends need to change the default bindings
to resolve conflicts.
