Incomplete validation in `tf.summary.create_file_writer`

Impact

If tf.summary.create_file_writer is called with non-scalar arguments code crashes due to a CHECK-fail.

```python

import tensorflow as tf

import numpy as np

tf.summary.create_file_writer(logdir='', flush_millis=np.ones((1,2)))

`

Patches

We have patched the issue in GitHub commit [874bda09e6702cd50bac90b453b50bcc65b2769e](https://github.com/tensorflow/tensorflow/commit/874bda09e6702cd50bac90b453b50bcc65b2769e) (merging [#51715](https://github.com/tensorflow/tensorflow/pull/51715)).

The fix will be included in TensorFlow 2.7.0. We will also cherrypick this commit on TensorFlow 2.6.1, TensorFlow 2.5.2, and TensorFlow 2.4.4, as these are also affected and still in supported range.

For more information

Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions.

Attribution

This vulnerability has been reported externally via a [GitHub issue](https://github.com/tensorflow/tensorflow/issues/46909).