- Implemented mipmap generation and completeness checks for
  Texture2DArray.
- Fixed texture parameters setters and getters along with
  mipmap generation functions to use the proper 2D array
  texture instead of the 3D texture for 2D array textures.
- Enabled the same path as 3D texture for 2D array textures
  in the sampler.
- Added an address function for the w component, which
  simply clamps the rounded value for 2D array textures and
  adapted SamplerCore::computeIndices to this new behavior.

Change-Id: Ida0659afac75330bfd9af4052cfd2625c729f9ef
Reviewed-on: https://swiftshader-review.googlesource.com/4310Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>