geotargets 0.2.0

• Created tar_stars() and tar_stars_proxy() that create stars and stars_proxy objects, respectively.
• Created tar_terra_tiles(), a "target factory" for splitting a raster into multiple tiles with dynamic branching (#69).
• Created two helper functions for use in tar_terra_tiles(): tile_grid(), tile_n(), and tile_blocksize() (#69, #86, #87, #89).
• Created utility function set_window() mostly for internal use within tar_terra_tiles().
• Removes the iteration argument from all tar_*() functions. iteration now hard-coded as "list" since it is the only option that works (for now at least).
• Added the description argument to all tar_*() functions which is passed to tar_target().
• Suppressed the warning "[rast] skipped sub-datasets" from tar_terra_sprc(), which is misleading in this context (#92, #104).
• Requires GDAL 3.1 or greater to use "ESRI Shapefile" driver in tar_terra_vect() (#71, #97)
• geotargets now requires targets version 1.8.0 or higher
• tar_terra_rast() gains a preserve_metadata option that when set to "zip" reads/writes targets as zip archives that include aux.json "sidecar" files sometimes written by terra (#58)
• terra (>= 1.7.71), withr (>= 3.0.0), and zip are now required dependencies of geotargets (moved from Suggests to Imports)