Fixes after options, terra, and `tar_terra_sprc()` updates

[brownag]

Here are some things I noticed while bringing the tar-stars (#33) branch up to date. Doing a separate PR as they are not related to the {stars} changes

In this PR:

• geotargets_option_get(): Handle case when getOption() returns vector length >1

• get_gdal_available_driver_list(): Fix for terra::gdal(drivers=TRUE) table format. This has changed in the development version of terra (currently 1.7-75 vs. CRAN 1.7-71). For now handle older package versions differently by checking with packageVersion() before subsetting driver list. {terra} now reports drivers similarly to how {sf} does RE: https://github.com/rspatial/terra/issues/1465

• tar_terra_sprc(): Fix specification of multiple raster creation options in test and add snapshot

[njtierney]

This looks great to me and passes checks - thanks for submitting, @brownag !