Add tf_control type and allow $ in bare-id.

* Add tf_control as primitive type;
* Allow $ in bare-id to allow attributes with $ (to make it trivially to mangle a TF attribute);

PiperOrigin-RevId: 206342642
diff --git a/lib/IR/AsmPrinter.cpp b/lib/IR/AsmPrinter.cpp
index e53962e..26cb1fc 100644
--- a/lib/IR/AsmPrinter.cpp
+++ b/lib/IR/AsmPrinter.cpp
@@ -287,6 +287,9 @@
   case Type::Kind::F64:
     os << "f64";
     return;
+  case Type::Kind::TFControl:
+    os << "tf_control";
+    return;
 
   case Type::Kind::Integer: {
     auto *integer = cast<IntegerType>(type);