incorporate support for multi-format resources

[alenastern]

• Review edits in Eli’s PR
• Create new branch (staging or multi-format-resource-support) and modify Eli’s PR Add support for resource argument w/ improved support for spatial data inputs #8 to merge into that branch
• Merge PR into new branch
• Open PR from new branch into main
• Run existing test suite on the updated code to see if anything fails (or we need to modify tests)
• Add internal instructions for how to use sedtR with the staging api (modify zzz.R and sedt_url() fxn)
• Add additional tests of functionality if needed beyond tests/testthat/test-prep_sedt_resource.R