patch 8.2.4012: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move the last error messages to errors.h.
diff --git a/src/if_python.c b/src/if_python.c
index 06d45d8..90f75ec 100644
--- a/src/if_python.c
+++ b/src/if_python.c
@@ -951,7 +951,7 @@
 	site = PyImport_ImportModule("site");
 	if (site == NULL)
 	{
-	    emsg(_("E887: Sorry, this command is disabled, the Python's site module could not be loaded."));
+	    emsg(_(e_sorry_this_command_is_disabled_python_side_module_could_not_be_loaded));
 	    goto fail;
 	}
 	Py_DECREF(site);