feat(client-s3): make expect continue header configurable

[kuhe]

Issue

partially addresses #6940

Description

Makes the expect: 100-continue header configurable by the S3 client.

Testing

new unit and integration tests, CI

Checklist

• If the PR is a feature, add integration tests (*.integ.spec.ts).
• If you wrote E2E tests, are they resilient to concurrent I/O?
• If adding new public functions, did you add the @public tag and enable doc generation on the package?