Settings: Set key order on addition

When the activity is created, injected preferences were not setting their order. This could potentially lead to two bottom preferences
in a given category on rebind. Ensure the order is set during key addition to prevent such issues.

Follow up to change: I1dc0148c5595f20daf026970d6514e63776b0499

Change-Id: I9df0bafbc2d2eddde94f07104d803fdc46adec8c
Signed-off-by: AnierinB <anierin@evolution-x.org>