[osipovartem]

Summary

• Route IS DISTINCT FROM and IS NOT DISTINCT FROM through the existing null-safe (<=>) binary expression planner hook.
• Preserve the original logical operators when planners leave operands unchanged; invert a fully planned null-safe expression for IS DISTINCT FROM.
• Cover unchanged behavior, rewritten operands, and fully planned expressions.

Verification

• cargo +1.95.0 test -p datafusion-sql --test sql_integration --offline: 656 passed.
• cargo +1.95.0 clippy -p datafusion-sql --tests --offline -- -D warnings -A clippy::nonminimal_bool: passed; waiver is for pre-existing warnings in datafusion-expr.
• Independent read-only review: approved with no blocking findings.