Normalise gesture identifiers in the process of binding them so that they match other...

Normalise gesture identifiers in the process of binding them so that they match other identifiers for the same gesture.
This is necessary because the order of the modifiers in a keyboard gesture (e.g. control+shift+alt) doesn't matter as far as the user is concerned, but NVDA needs them to be in a determinate order so they match other identifiers.
Currently, this is implemented in inputCore.normalizeGestureIdentifier(). This also converts the string to lower case, which used ot be done in ScriptableObject.bindGesture().
This may need to be made specific to the type of gesture in future; e.g. braille gesture identifiers might need different normalisation. However, this can be done later if necessary.