Blender Git Loki

Compositor: Add sampling methods for full frame

Current sampling methods do not take into account area offsets
and have some off by 1 issues on full frame. For example on bilinear
bottom and left image border pixel is not fully sampled and
creates edges.
Other issue is they use `wrap_pixel` when most of the time is not
needed.

In order to not affect tiled implementation, this commit creates
specific sampling methods for full frame needs.