bug(windows): numberpad keys "/, *, -, +" are either not being added or resetting the context in non-compliant apps

[rc-swag]

In testing #11172 it was discovered we currently doesn't handle the numberpad keys "/;*;-;+" well in non-compliant apps. The context is either reset when they are pressed or not added to the context at all.

Steps to preproduce.

Non-compliant
Load euro-latin keyboard

1. Press 1
2. Using the number pad press / /
3. Press 2
   The result is:
   1//2
   instead of:
   ½

Non-compliant context reset

1. Press a
2. Using the number pad press *
   the result is:
   a*
   instead of:
   Star

[mcdurdin]

I am going to push this to 18.0 as lower priority.