Importing of terra and sf

[mhesselbarth]

The calls to #' @import terra and #' @import sf in project and add_biodiversity import the entire Namespace of the two packages. Not really an issue, but certainly not good style. However, removing this would require some modifications to the code cause some imports wouldn't be known anymore. Yet, currently this issue is kind of hidden by the fact that the entire Namespace is imported.

[Martin-Jung]

Flagged as low priority as I don't think this issue breaks anything at the moment.