KiCad: add pcb and schematic lock file patterns

[mlilley]

KiCad creates lock files when schematic and/or pcb is open, that should not be included in repos:

~.kicad_pcb.lck ~.kicad_sch.lck

These files are unfortunately not mentioned in the documentation, but are used on at least macos with KiCad v8.0. I am not affiliated with the KiCad project, lest, only a lowly user.

https://www.kicad.org/