remove usage of WarpedVRT?

Since the creation of rio-tiler we have had multiple issues with WarpedVRT (latest one #654), I think we should try to remove its usage! 


With WarpedVRT the reprojection and reading happens at the same time, but in theory we could do the `reading` from the initial dataset and then reproject using https://github.com/rasterio/rasterio/blob/main/rasterio/warp.py#L161-L165 

 
