Rollup merge of #136910 - okaneco:sig_ones, r=thomcc

Implement feature `isolate_most_least_significant_one` for integer types

Accepted ACP - https://github.com/rust-lang/libs-team/issues/467
Tracking issue - #136909

Implement ACP for functions that isolate the most significant set bit and least significant set bit on unsigned, signed, and `NonZero` integers.

Add function `isolate_most_significant_one`
Add function `isolate_least_significant_one`

---

This PR adds the following impls
```rust
impl {u8, u16, u32, u64, u128, usize} {
    const fn isolate_most_significant_one(self) -> Self;
    const fn isolate_least_significant_one(self) -> Self;
}
impl {i8, i16, i32, i64, i128, isize} {
    const fn isolate_most_significant_one(self) -> Self;
    const fn isolate_least_significant_one(self) -> Self;
}
impl NonZeroT {
    const fn isolate_most_significant_one(self) -> Self;
    const fn isolate_least_significant_one(self) -> Self;
}
```
Example behavior
```rust
assert_eq!(u8::isolate_most_significant_one(0b01100100), 0b01000000);
assert_eq!(u8::isolate_least_significant_one(0b01100100), 0b00000100);
```

0 files changed, 0 insertions, 0 deletions