Fix T78823: Slash in custom property name does not work

Some characters: `'`, `"`, and `\`, can cause problems with RNA paths.
Instead of using more complicated handling to deal with those cases,
we can just prevent these characters from being used in custom property
names.

This commit checks for these characters to `idp_try_read_name`, where
other checks like length are already done.

Differential Revision: https://developer.blender.org/D8839

source/blender/python/generic/idprop_py_api.c

@@ -20,6 +20,8 @@
 
 #include <Python.h>
 
+#include <string.h>
+
 #include "MEM_guardedalloc.h"
 
 #include "BLI_utildefines.h"
@@ -370,6 +372,11 @@ static const char *idp_try_read_name(PyObject *name_obj)
                       "the length of IDProperty names is limited to 63 characters");
       return NULL;
     }
+
+    if (strchr(name, '\"') || strchr(name, '\\') || strchr(name, '\'')) {
+      PyErr_SetString(PyExc_KeyError, "IDProperty names cannot include \", \\, or \'");
+      return NULL;
+    }
   }
   else {
     name = "";