refactor(arrow2): migrate time.rs temporal methods to arrow-rs (#6160)

## Summary
- Replace arrow2 temporal kernels (`daft_arrow::compute::temporal::*`)
with unified `arrow::compute::date_part()` API for **DateArray** (8
methods), **TimestampArray** (3 methods), and **TimeArray** (6 methods)
- Migrate iterator-based methods (`date`, `time`, `truncate`,
`unix_date`) from `as_arrow2()` to `as_arrow()` with
`DataArray::from_iter` / `Int64Builder` construction
- Remove `ArraySub` and `Timelike` imports no longer needed after
migration
- Interval operations (`add_interval`, `sub_interval`,
`IntervalArray::mul`) deferred to follow-up PR -- no arrow-rs equivalent
for interval arithmetic yet

Ref: #5741

Net change: **-258 lines** (110 added, 368 removed)

## Test plan
- [x] `cargo check -p daft-core` -- no new warnings
- [x] `cargo check -p daft-core --all-features` -- passes (pre-commit
hook)
- [x] `cargo test -p daft-core` -- all 312 tests pass
- [x] `clippy` -- passes
- [x] `rustfmt` -- passes

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: rohitkulshreshtha