[debugserver] Various plist changes

 - Remove unused plists that were referenced (but unused) by Xcode.
 - Move all debugserver plists unders tools/debugserver/resources.
 - Add the ability to distinguish between com.apple.security.cs.debugger
   and com.apple.private.cs.debugger.

rdar://66082043

Differential revision: https://reviews.llvm.org/D94320