Add stitched phase cosine similarity raster to outputs

[scottstanie]

The cosine similarity metric from Wang, 2022 works as a quality metric outside the context of PS.

Since the temporal coherence for small (~ 20 or fewer SLCs) ministacks does not have a large dynamic range, this can be used as an alternative way to filter out bad pixels.

E.g. for 35 SLCs over Hawaii (over 3 ministacks), the mean temporal_coherence.tif looks like this plotting 0 to 1:

while the similarity using nearest-3 interferograms looks like this: