S3 URL parsing: verify hostname case sensitivity and fix endpoint comparison

[coderabbitai]

Context

Related to PR #1767 and this comment.

@junhaoliao raised a concern that the regex patterns in the S3 URL parsing code prohibit uppercase letters, which are technically allowed per RFC952.

Tasks

1. Verify hostname and path case sensitivity behavior

   • Confirm if hostname is case insensitive
   • Confirm if path is case sensitive
   • Update regex patterns accordingly if uppercase letters should be allowed in hostnames

2. Fix endpoint comparison to be case insensitive

   • The comparison endpoint != AWS_ENDPOINT in parse_s3_url (line 318 in components/clp-py-utils/clp_py_utils/s3_utils.py) needs to be case insensitive
   • Similar fixes may be needed in the C++ code

Affected Files

• components/clp-py-utils/clp_py_utils/s3_utils.py
• components/core/src/clp/aws/constants.hpp
• components/core/src/clp/aws/AwsAuthenticationSigner.cpp

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Requested by: @hoophalab
PR: #1767