do not wrap the input dataset in a WarpedVRT when it's not needed

[vincentsarago]

By default cog_translate will use an intermediate WarpedVRT during the processing, this is mostly to:

• enable WebOptimized wrapping
• enable nodata/alpha translation to mask
• datatype casting (not sure if WarpedVRT is needed for this)

rio-cogeo/rio_cogeo/cogeo.py

Line 271 in c9ffcae

with WarpedVRT(src_dst, **vrt_params) as vrt_dst:

But it has the inconvenience of automatically wrapping dataset with internal GCPS, meaning that input dataset with GCPS will result in output dataset wrapped using the GCPS.