Wofs

* Include USGS C2 data handling

* Minor change to digital elevation model handling, adding a small buffer around the edges to prevent artefacts in the terrain shadow map.

The algorithm changes made is the 1.5.5 release are **significant**, and should not have been published as a minor point release.

This release is identical to v1.5.6, but will be the version used going forward for GA Collection 3 processing.

For any Collection 2 processing related fixes, we should fork from v1.5.4 only, and avoid using 1.5.5 or 1.5.6 or 1.6+.

Changes

- Fixes a bug in the VirtualProduct Transform implementation caused by a pandas time selection bug
- Updates to the algorithm parameters:

- bit mask - replace sea mask bit (already not using) with low solar incidence angle mask; terrain shadow mask has its own bit.
- low solar incidence threshold reduced to 10 (not masking out high latitude region in window).
- replace hard-coded pixel scale in shadow calculation.
- use bilinear resampling for DSM.

This release fixes a bug introduce in early 2020, which disabled the filtering out of poorly geolocated input datasets based on their GQA values.

This is specifically for the Collection 2 WOfS processing, running on the NCI, using `datacube-wofs`.

- Fix bug that was confusing no-data and non-contiguous flagging.
- Remove USGS C2 hack

- Fixes a bug in the VirtualProduct Transform implementation caused by a pandas time selection bug
- Updates to the algorithm parameters:

- bit mask - replace sea mask bit (already not using) with low solar incidence angle mask; terrain shadow mask has its own bit.
- low solar incidence threshold reduced to 10 (not masking out high latitude region in window).
- replace hard-coded pixel scale in shadow calculation.
- use bilinear resampling for dsm.