Support verifying multiple artifacts in one go when they share a single attestations bundle?

[mara004]

Description

Consider the case where you have a series of artifacts with a single attestation bundle produced by actions/attest-build-provenance, respectively actions/attest.

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Example:

• Just sigstore verify github --repository bblanchon/pdfium-binaries pdfium-linux-x64.tgz fails, logically:
  sigstore: error: Missing verification materials for pdfium-linux-x64.tgz: pdfium-linux-x64.tgz.sigstore.json

• When passing the right bundle, it works:
  sigstore verify github --repository bblanchon/pdfium-binaries pdfium-linux-x64.tgz --bundle pdfium-7906-attestation.json
OK: pdfium-linux-x64.tgz

• When adding another artifact, however:
  sigstore verify github --repository bblanchon/pdfium-binaries pdfium-linux-x64.tgz pdfium-linux-x86.tgz --bundle pdfium-7906-attestation.json
sigstore: error: --certificate, --signature, or --bundle can only be used with a single input file or digest
  Help says not used with multiple inputs (default: None)

• Note that verifying pdfium-linux-x86.tgz individually with the same bundle again works:
  sigstore verify github --repository bblanchon/pdfium-binaries pdfium-linux-x86.tgz --bundle pdfium-7906-attestation.json
OK: pdfium-linux-x86.tgz

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Sure, one could loop on the caller side, but that's neither particularly ergonomic nor efficient.
Why not support verifying multiple artifacts in one go when they share one attestations bundle?

Thanks.