fix: avoid panic in date_bin compute_distance near i64::MIN

[SAY-5]

Which issue does this PR close?

• Closes panic: date_bin compute_distance subtracts past i64::MIN #22215.

Rationale for this change

date_bin panics with attempt to subtract with overflow when the source timestamp sits near i64::MIN because compute_distance does time_diff - (time_diff % stride) and then time_delta - stride on raw i64. The scalar pipeline already maps Err from bin_fn into NULL, so the fix is to surface the overflow as a normal error.

What changes are included in this PR?

• Convert compute_distance to return Result<i64> and use checked_sub.
• Propagate the result through date_bin_nanos_interval and date_bin_months_interval, plus replace the trailing origin + time_delta with checked_add.

Are these changes tested?

Yes. Added test_date_bin_compute_distance_i64_min which previously panicked and now returns NULL. Ran cargo test -p datafusion-functions --lib -- datetime::date_bin, cargo fmt --check, and cargo clippy -p datafusion-functions --lib --tests --no-deps.

Are there any user-facing changes?

Queries that previously panicked on extreme timestamps now return NULL (consistent with the existing out-of-range behavior covered by test_date_bin_out_of_range).