[Fix] Clean up all explict DataLoader usage

[haochengxia]

• We cleaned up all outdated usage and descriptions on DataLoader
• We removed the deprecated API for the pybind error.

[gemini-code-assist]

Summary of Changes

Hello @haochengxia, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on simplifying the data loading workflow by deprecating the explicit DataLoader and enabling TraceReader to directly handle S3 URIs. This change reduces boilerplate code and makes the API more intuitive for users. Additionally, it includes an update to a core submodule and a minor but important fix for how C++ exceptions are exposed to Python, enhancing overall stability and developer experience.

Highlights

• Simplified Trace Loading: The explicit DataLoader class has been removed, allowing TraceReader to directly accept S3 URIs for loading cache trace files. This streamlines the process of accessing remote data.
• Documentation and Example Updates: The quickstart guide and example scripts (s3fifo.py, trace_analysis.py) have been updated to reflect the new, simplified trace loading mechanism, ensuring consistency and ease of use.
• Improved Exception Handling: C++ exception handling within the Python bindings has been refined to use py::set_error, ensuring more robust and idiomatic propagation of CacheException and ReaderException to Python.
• Submodule Update: The libCacheSim submodule has been updated to its latest commit, incorporating any upstream changes or fixes.

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[gemini-code-assist]

Code Review

This pull request cleans up the explicit usage of DataLoader by allowing TraceReader to handle S3 URIs directly. The changes in the examples and documentation reflect this new, simpler workflow. My review focuses on ensuring the documentation is accurate and that a potential issue in the C++ exception handling is addressed.

I've found a couple of issues in the documentation that need fixing: a broken code example and an incorrectly numbered list. More importantly, I've identified a bug in src/exception.cpp where the exception translator for custom exceptions is shadowed by a more generic one, which would prevent custom exceptions from being raised in Python. Please see my detailed comments for suggestions.