test: move lead/lag extreme-offset regressions to sqllogictest

[Dandandan]

Motivation

• Ensure extreme lead/lag offset regressions are validated at the SQL-level (sqllogictest) rather than as Rust unit tests to match review guidance and exercise the public execution path.
• Prevent panics and overflow from extreme offsets by keeping the earlier evaluator fixes (safe negation and checked arithmetic) in place and ensuring behavior is observable from SQL tests.

Description

• Change WindowShiftKind::shift_offset to return Result<i64> and use checked_neg() for lead to reject i64::MIN with a descriptive execution error.
• Update partition_evaluator to propagate the Result and apply reversal for reversed evaluators.
• Replace unchecked index arithmetic in WindowShiftEvaluator::evaluate with checked subtraction and safe usize conversion to avoid overflow/panic for extreme offsets.
• Remove two Rust unit tests that asserted the extreme-offset behaviors and add datafusion/sqllogictest/test_files/lead_lag_extreme_offsets.slt which covers both cases at the SQL level: lead(value, -9223372036854775808, 0) produces an execution error and lead(value, 9223372036854775807, 0) returns the provided default for all rows.

Testing

• Ran cargo fmt --all, which completed successfully.
• Ran cargo clippy --all-targets --all-features -- -D warnings, which failed due to a pre-existing, unrelated compile error in datafusion/physical-plan/benches/aggregate_vectorized.rs.
• Attempted targeted SQL-level test with cargo test -p datafusion-sqllogictest --test sqllogictests -- lead_lag_extreme_offsets, but a full build/run could not be completed in this environment due to heavy compilation and build locking; recommend CI to run the new sqllogictest file during PR validation.

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Codex Task