xarray_open_dataset when using a reference file should allow for anon = True or False

[abarciauskas-bgse]

This anon parameter should not be hardcoded as True, as it is right now: https://github.com/developmentseed/titiler-xarray/blob/main/titiler/xarray/reader.py#L37. This is because some datasets are in protected buckets and the titiler must have access to them to properly interpret kerchunk references.

I also experienced odd behavior when it is set as True and needs to be False.

When it's True, it will open the dataset but with the lat and lon incorrectly decoded:

Coordinates:
  * lat        (lat) float64 0.0 1.514e+241 0.0 ... 2.555e-314 2.167e-314
  * lon        (lon) float64 0.0 -3.405e-130 0.0 ... 1.141e+243 7.982e-289
  * time       (time) datetime64[ns] 1950-01-16T12:00:00 ... 1951-12-16T12:00:00

When it is False, it properly decodes the coordinates.