Add: Push switches with shield pins
This adds:
- SW_Push_Shielded - a generic symbol
- Two atomic inheritors:
- CK_KMS2xxG - a push button switch
- CK_KMS2xxGP - a variant with mounting pegs
- Two atomic inheritors:
https://www.ckswitches.com/media/1482/kms.pdf
We already have footprints for these parts that uses the SH pins and 1/2 for the contacts:
