Add test dataset with different projection/grid

[adebardo]

Context

Currently, both of our test datasets for Longyearbyen use the same grid. This means that the reprojection logic is only being tested in a very limited way. To improve the robustness of our tests, we should introduce a new DEM (Digital Elevation Model) dataset that uses a different projection or grid.

Steps

• [ ] Select a DEM dataset with a different grid/projection. (maybe see demcompare's ones)

• [ ] Add this new DEM to the test datasets.

• [ ] Update the automated tests to include this new dataset.

• [ ] Ensure that the reprojection logic is effectively tested with this new case.

• [] add a test with an int dataset too

Estimate 2d

[rhugonnet]

FYI: Joins this issue: https://github.com/GlacioHack/xdem/issues/635