Set up requester pays

[zaneselvans]

After having a few $20 days, we've decided to limit our exposure to unexpected data egress fees by turning on Requester Pays for the storage buckets containing the pudl-catalog.

• [x] Enable requester pays on gs://intake.catalyst.coop
• [x] Make the tests supply a billing project so they can access the storage buckets.
• [x] Check that we're only downloading a minimal amount of data (a couple of state-years) in the tests.
• [x] Update the example notebook to use requester_pays and new dd.read_parquet() args.
• [x] Provide documentation / links for setting up a user billing project in the README.

[zaneselvans]

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