Auto merge of #36072 - arthurprs:binary_heap_opt, r=Aatch
Optimize BinaryHeap bounds checking
I was experimenting with d-ary binary heaps during the weekend (dead end) and I found that we could get some good improvements by removing bounds checking. Specially due to the panic-safe additional code, llvm can't really optimize them out.
```
name d_ary_heap:: ns/iter std___heap:: ns/iter diff ns/iter diff %
bench_build_insert 148,610 236,960 88,350 59.45%
bench_from_vec 243,846 299,719 55,873 22.91%
bench_insert_2000_empty 4,512 7,517 3,005 66.60%
bench_insert_2000_prefilled 28,665 32,605 3,940 13.74%
bench_pop_2000 111,515 128,005 16,490 14.79%
bench_pop_all 2,759,945 3,317,626 557,681 20.21%
peek_mut 23,186 23,635 449 1.94%
pop_modify_push 41,573 43,822 2,249 5.41%
test d_ary_heap::bench_build_insert ... bench: 148,610 ns/iter (+/- 10,687)
test d_ary_heap::bench_from_vec ... bench: 243,846 ns/iter (+/- 16,500)
test d_ary_heap::bench_insert_2000_empty ... bench: 4,512 ns/iter (+/- 136)
test d_ary_heap::bench_insert_2000_prefilled ... bench: 28,665 ns/iter (+/- 1,347)
test d_ary_heap::bench_pop_2000 ... bench: 111,515 ns/iter (+/- 104,677)
test d_ary_heap::bench_pop_all ... bench: 2,759,945 ns/iter (+/- 173,838)
test d_ary_heap::peek_mut ... bench: 23,186 ns/iter (+/- 106,254)
test d_ary_heap::pop_modify_push ... bench: 41,573 ns/iter (+/- 3,313)
test std___heap::bench_build_insert ... bench: 236,960 ns/iter (+/- 16,955)
test std___heap::bench_from_vec ... bench: 299,719 ns/iter (+/- 6,354)
test std___heap::bench_insert_2000_empty ... bench: 7,517 ns/iter (+/- 372)
test std___heap::bench_insert_2000_prefilled ... bench: 32,605 ns/iter (+/- 2,433)
test std___heap::bench_pop_2000 ... bench: 128,005 ns/iter (+/- 11,787)
test std___heap::bench_pop_all ... bench: 3,317,626 ns/iter (+/- 238,968)
test std___heap::peek_mut ... bench: 23,635 ns/iter (+/- 1,420)
test std___heap::pop_modify_push ... bench: 43,822 ns/iter (+/- 3,788)
```
Test code: https://github.com/arthurprs/heap-experiments