CAS-14527 : Improve AWP2 memory performance
The wtcf for A-term was duplicated across all W planes. This is not
strictly necessary, since A term wtcf is independent of W. The code has
been refactored to reflect this.
From VLASS testing this was a ~ 20-30% drop in sustained memory load.
CAS-14527 : Memory improvement to W-plane CFs
Instead of allocating a large buffer and trimming down to max W support
size, calculate the max W support size a priori and create a buffer that
is 2X that size (same as the post-trim size before this change).
From VLASS testing, this yields a ~ 40% drop in peak memory required,
although this is very dependent on max W support size.
CAS-14527 : Incremental gridding performance
The gridder discarded (prior to this commit) the per-W support size and
always used the largest support size.
This change respects the computed per-W support size during gridding,
therefore small W planes see a speedup and do not waste time gridding
with effectively padding.
