gh-126654: Fix crash in several functions in _interpreters module

[sobolevn]

This was the cause:

• We checked that passed arg is not a dict here:

  cpython/Python/crossinterp.c

  Lines 1479 to 1482 in 6ee542d

  	if (!PyDict_CheckExact(nsobj)) {
  	PyErr_SetString(PyExc_TypeError, "expected a dict");
  	return NULL;
  	}

• Later we had an assertion about !PyErr_Occurred()

So, I went with the early validation.

• Issue: _interpreters.exec with invalid parameters segfaults #126654

[miss-islington-app]

Thanks @sobolevn for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-126681 is a backport of this pull request to the 3.13 branch.