MLBEDSW-7648: Fix bug with filter padding in conv2d

* Fix bug that caused filter padding to not be added proportionally
  compared to the hardware padding added to IFM.
* Update needed_total_padding function that calculates hardware padding
  to also account for the cases in which IFM width is not divisible by
  the stride width.
* Update supported ops constraint on strides for conv2d to mark ops with
  stride width > 3 and IFM width that is not divisible by the
  optimization resize factor as not supported.
* Update unit tests that verify correct functionality when checking
  whether ops are supported or not.

Change-Id: I62f14cca890b779ca787a9603fa37c873ad522f8
Signed-off-by: Raul Farkas <raul.farkas@arm.com>