[llvm] [GlobalISel] Add `GITypeOf` special type (PR #66079)

[Matt Arsenault via llvm-commits]

================
@@ -274,6 +276,12 @@ enum {
   /// - StoreIdx - Store location in RecordedOperands.
   GIM_RecordNamedOperand,
 
+  /// TODO DESC
----------------
arsenm wrote:

TODO?

https://github.com/llvm/llvm-project/pull/66079