Range-request based metadata extraction for point clouds

[olsen232]

Description

Use PDAL 2.6 to extract metadata from s3 directly, instead of downloading first. Arbiter upstream now supports AWS_NO_SIGN_REQUEST, but the version vendored into PDAL 2.6.0 doesn't have this yet. Added this into the overlay. We use this to make authless requests during testing.

Checklist:

• [x] Have you reviewed your own change?
• [ ] Have you included test(s)?
• [ ] Have you updated the changelog?