make `dismo::mess` for the new era of `terra`

[geryan]

Currently dismo::mess requires stuff to be in raster format https://github.com/idem-lab/vector_sdm_course/blob/58c3c26d9522341115fa9ca7cb896f295fc62c42/R/mess_intro.R#L3

In a spare moment one shall simply rewrite the guts of this so it sucks in and spits out SpatRaster objets in order to not have to go terra -> raster -> terra

Garn

[geryan]

this might already exist: https://github.com/cebra-analytics/bssdm/blob/main/R/mess.R