[flang] Add notify-type and notify-wait-stmt (#76594)

Add `notify-type` to `iso_fortran_env` module. Add `notify-wait-stmt` to
the parser and add checks for constraints on the statement, `C1177` and
`C1178`, from the Fortran 2023 standard. Add three semantics tests for
`notify-wait-stmt`.
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index e1d406e..2bceee0 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -3092,6 +3092,10 @@
 
   //===--------------------------------------------------------------------===//
 
+  void genFIR(const Fortran::parser::NotifyWaitStmt &stmt) {
+    genNotifyWaitStatement(*this, stmt);
+  }
+
   void genFIR(const Fortran::parser::EventPostStmt &stmt) {
     genEventPostStatement(*this, stmt);
   }