* Unit tests for conv2d causing errors.

* UT for conv3D_bias

* Fix padding order.

`padding below` in nGraph terminology means padding added at the beginning
of the axis. Whereas `padding above` means padding added at the end of
the axis.

* Rename test to sth more descriptive.

* Apply clang-format.

* Fix handling of `SAME_UPPER/LOWER` auto_pads mode for convolution/pooling ops.

* Fix order of padding_below/above.
Signed-off-by: Adam Rogowiec <adam.rogowiec@intel.com>

* Fix error in calculating output data shape.