Shared CFG: check abrupt completion origins

[yoff]

Summary

• add invalidAbruptCompletionOrigin to the shared CFG consistency checks;
• validate only language-supplied Input2::beginAbruptCompletion origins, requiring each origin to be either node.isIn(ast) or node.isAdditional(ast, _);
• register the check in consistencyOverview and add generated overview tests for every current consumer: Java, C#, and Python.

This intentionally does not inspect the shared library's combined private beginAbruptCompletion, whose unmatched final catch-clause completion legitimately originates at isAfterValue.

Motivation

This follows the consistency-check suggestion from review of github#22380: github#22380 (comment). The change is independent of github#22380 and contains no Python-specific CFG behavior change.

Validation

• codeql query compile --search-path=. java/ql/consistency-queries/CfgConsistency.ql csharp/ql/consistency-queries/CfgConsistency.ql python/ql/consistency-queries/CfgConsistency.ql
• codeql test run --search-path=. --consistency-queries java/ql/consistency-queries -- java/ql/test/library-tests/controlflow/basic — 28 tests passed
• codeql test run --search-path=. --consistency-queries csharp/ql/consistency-queries -- csharp/ql/test/library-tests/controlflow/graph — 13 tests passed
• codeql test run --search-path=. --consistency-queries python/ql/consistency-queries -- python/ql/test/library-tests/ControlFlow/successors — 7 tests passed

No invalid abrupt-completion origins or unrelated expected-output churn were found in the three consuming languages.

[yoff]

Closing in favor of the upstream pull request against github/codeql:main.