C++: Add DB schema support for coroutines

cpp/ql/src/semmlecode.cpp.dbscheme

@@ -1647,6 +1647,8 @@ case @expr.kind of
 | 324 = @builtinconvertvector
 | 325 = @builtincomplex
 | 326 = @spaceshipexpr
+| 327 = @co_await
+| 328 = @co_yield
 ;
 
 @var_args_expr = @vastartexpr
@@ -1851,6 +1853,8 @@ case @stmt.kind of
 |  33 = @stmt_handler
 // ...  34 @stmt_finally_end deprecated
 |  35 = @stmt_constexpr_if
+|  37 = @stmt_co_return
+|  38 = @stmt_range_based_for_co_await
 ;
 
 type_vla(