Deprecate "rgb by default" raster upload flow

[stephanerestani-picterra]

The current default behavior for upload_raster is to set multispectral=False, which ends up dropping the non-rgb bands during normalization.

This doesn't match the default behavior on the platform and is error-prone, but this was kept for backward-compatibility.

Let's deprecate the current upload_raster (make it raise a DeprecationWarning and replace it with a new function that does the "right" thing (multispectral=True by default).

[ao-picterra]

Fixed in 145da10, but we should make a new release bc otherwise pip install will still have a bug