Fix discrepancy between docs and registered kernels for `tf.ones_like`/`tf.zeros_like` (#13598)

* Fix discrepancy between docs and registered kernels for `tf.ones_like`

This fix tries to address the discrepancy between docs and registered
kernels for `tf.ones_like`. From the implementation the OnesLike is
registered with all POD types. However, in the documentation several
data types are missing (uint8, int8, uint16, int16, bool).

This fix addresses the issue by adding missing types to documentation.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix python docs for `tf.ones_like`

This commit fixes python docs for `tf.ones_like`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix python docs for `tf.zeros_like`

This commit fixes python docs for `tf.zeros_like`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add test cases for different dtypes on `tf.ones_like` and `tf.zeros_like`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>