gh-144569: Avoid creating temporary objects in BINARY_SLICE for bytes

[koxudaxi]

Add an exact bytes fast path to BINARY_SLICE, following the list, tuple, and unicode fast paths added in gh-144590. This avoids creating a temporary slice object. Bytes subclasses continue to use the generic path.

Teach the Tier 2 optimizer that slicing an exact bytes object returns an exact bytes object.

Benchmark

Release builds on macOS arm64. Each result is the median of nine alternating runs after two warmups. Each sample ran in a fresh process.

Benchmark	main	this PR	Change
Partial bytes slice, 5 million operations	347.717 ms	310.204 ms	10.8% faster
Full bytes slice, 5 million operations	274.867 ms	246.176 ms	10.4% faster
base64.b64encode with altchars, 3 million operations	562.155 ms	533.675 ms	5.1% faster

There was no measurable change in peak RSS.

Tests

The full debug test suite passed with 50,671 tests using 14 workers.

Focused tests passed on debug, free-threaded, and JIT builds. test_bytes and test_slice also passed a -R 3:3 refleak run.

• Issue: Avoid creating temporary objects in BINARY_SLICE #144569