chore(bigframes): Add simple Python bytcode translation

[TrevorBergeron]

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Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Code Review

This pull request introduces bytecode compilation to BigQuery expressions, along with custom expression classes and unit tests. The reviewer feedback highlights several opportunities for improvement, including handling variables explicitly set to None in LOAD_GLOBAL, refactoring repetitive blocks for older Python binary operations using a module-level mapping, guarding against a potential AttributeError when op_symbol is None in BINARY_OP, and fixing typos and copy-paste errors in exception messages.