FindPython*: Manage weak link for Python modules

Add new target Python::Module which take care of platform requirements
for Python module development.

Fixes: #18100

Tests/FindPython/display_time.c

@@ -0,0 +1,36 @@
+
+#include <stdio.h>
+
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+
+#include "display_time.h"
+
+void display_time()
+{
+#if defined(PYTHON3)
+  wchar_t* program = Py_DecodeLocale("display_time", NULL);
+  if (program == NULL) {
+    fprintf(stderr, "Fatal error: cannot decode argv[0]\n");
+    exit(1);
+  }
+  char* cmd = "from time import time,ctime\n"
+              "print('Today is', ctime(time()))\n";
+#else
+  char* program = "display_time";
+  char* cmd = "from time import time,ctime\n"
+              "print 'Today is', ctime(time())\n";
+#endif
+
+  Py_SetProgramName(program); /* optional but recommended */
+  Py_Initialize();
+  PyRun_SimpleString(cmd);
+#if defined(PYTHON3)
+  if (Py_FinalizeEx() < 0) {
+    exit(120);
+  }
+  PyMem_RawFree(program);
+#else
+  Py_Finalize();
+#endif
+}