Add local pre-signed URL placeholders

[srinivasBJ]

Summary

• return a clearly marked placeholder URL when local cloud paths are presigned
• preserve the requested expiry in the placeholder query parameters
• cover Azure, Google Cloud Storage, and S3 local implementations
• document that local placeholder URLs cannot access files

Closes #525

Testing

• make lint
• .venv/bin/python -m pytest -q
• 1019 passed, 5 skipped

Contributor checklist

• I have read and understood CONTRIBUTING.md
• Confirmed an issue exists for the PR, and the text Closes #issue appears in the PR summary
• Confirmed PR is based on the latest master
• Confirmed failure before change and success after change
• Any generic new functionality is replicated across cloud providers if necessary
• Tested manually against live server backend for at least one provider
• Added tests for the new functionality
• Linting passes locally
• Tests pass locally
• Updated HISTORY.md with the issue and PR addressed