Handle Python 3.11 exception opcodes in AST builder

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What changed

• add AST builder handling for Python 3.11 exception-related opcodes:
  • PUSH_EXC_INFO
  • CHECK_EXC_MATCH
  • RERAISE
  • RERAISE_A
  • BEFORE_WITH
• map CHECK_EXC_MATCH to ASTCompare::CMP_EXCEPTION
• synthesize try/except block structure from Python 3.11 exception table entries when legacy setup opcodes are absent
• preserve exception handler bounds so handler cleanup opcodes do not leak into decompiled source
• treat RERAISE cleanup opcodes as internal control-flow cleanup rather than emitted source statements
• add a Python 3.11 regression test for typed try/except

Why this changed

The AST builder did not recognize several Python 3.11 exception opcodes, and it also relied on legacy setup opcodes that are no longer present in 3.11 bytecode. That meant decompilation could stop early, lose except clauses, or emit cleanup artifacts instead of valid try/except source.

Impact

• improves compatibility with Python 3.11 bytecode around typed exception handling
• restores try/except structure from exception-table driven bytecode
• adds regression coverage for the new path without changing existing expected-failure coverage

Validation

• inspected and updated the opcode-specific AST builder path in ASTree.cpp
• configured a fresh build directory with:
  • /Users/miyazakidaichi/anaconda3/envs/dits2/lib/python3.11/site-packages/cmake/data/bin/cmake -S /Users/miyazakidaichi/Nextcloud/dev/tmp_pycdc -B /tmp/tmp_pycdc_build_codex
• built successfully with:
  • make -C /tmp/tmp_pycdc_build_codex -j4
• verified the new regression test in isolation with:
  • python3 /Users/miyazakidaichi/Nextcloud/dev/tmp_pycdc/tests/run_tests.py --filter test_exception_match_py311 --jobs 1
• ran the full test target successfully with:
  • make -C /tmp/tmp_pycdc_build_codex check JOBS=4
• existing expected-failure (XFAIL) cases still appear in the suite output