[llvm] Move CodeGenTypes library to its own directory (#79444)

Finally addresses https://reviews.llvm.org/D148769#4311232 :)

No behavior change.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 40e2f79..4765731 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -21,11 +21,11 @@
 #include "llvm/CodeGen/AssignmentTrackingAnalysis.h"
 #include "llvm/CodeGen/CodeGenCommonISel.h"
 #include "llvm/CodeGen/ISDOpcodes.h"
-#include "llvm/CodeGen/MachineValueType.h"
 #include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/SwitchLoweringUtils.h"
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/CodeGen/ValueTypes.h"
+#include "llvm/CodeGenTypes/MachineValueType.h"
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/Support/BranchProbability.h"