Module group: Move Bit.swift to Math.

Author: nkcsgexi

stdlib/public/core/GroupInfo.json

@@ -88,6 +88,7 @@
     "IntegerArithmetic.swift",
     "FixedPoint.swift",
     "IntegerParsing.swift",
+    "Bit.swift",
     "SetAlgebra.swift"
   ],
   "Optional": [
@@ -118,7 +119,6 @@
     "Shims.swift",
     "Unmanaged.swift",
     "Availability.swift",
-    "Bit.swift",
     "Process.swift",
     "Tuple.swift"
   ]