gh-76785: More Fixes for test.support.interpreters (gh-113012)

This brings the module (along with the associated extension modules) mostly in sync with PEP 734.  There are only a few small things to wrap up.

Modules/Setup

@@ -273,6 +273,7 @@ PYTHONPATH=$(COREPYTHONPATH)
 
 #_xxsubinterpreters _xxsubinterpretersmodule.c
 #_xxinterpchannels _xxinterpchannelsmodule.c
+#_xxinterpqueues _xxinterpqueuesmodule.c
 #_xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 #_testbuffer _testbuffer.c
 #_testinternalcapi _testinternalcapi.c

Modules/Setup.stdlib.in

@@ -41,8 +41,11 @@
 @MODULE__QUEUE_TRUE@_queue _queuemodule.c
 @MODULE__RANDOM_TRUE@_random _randommodule.c
 @MODULE__STRUCT_TRUE@_struct _struct.c
+
+# build supports subinterpreters
 @MODULE__XXSUBINTERPRETERS_TRUE@_xxsubinterpreters _xxsubinterpretersmodule.c
 @MODULE__XXINTERPCHANNELS_TRUE@_xxinterpchannels _xxinterpchannelsmodule.c
+@MODULE__XXINTERPQUEUES_TRUE@_xxinterpqueues _xxinterpqueuesmodule.c
 @MODULE__ZONEINFO_TRUE@_zoneinfo _zoneinfo.c
 
 # needs libm

Modules/_xxinterpchannelsmodule.c

@@ -2629,10 +2629,11 @@ _get_current_channelend_type(int end)
         cls = state->recv_channel_type;
     }
     if (cls == NULL) {
-        PyObject *highlevel = PyImport_ImportModule("interpreters");
+        // Force the module to be loaded, to register the type.
+        PyObject *highlevel = PyImport_ImportModule("interpreters.channel");
         if (highlevel == NULL) {
             PyErr_Clear();
-            highlevel = PyImport_ImportModule("test.support.interpreters");
+            highlevel = PyImport_ImportModule("test.support.interpreters.channel");
             if (highlevel == NULL) {
                 return NULL;
             }