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);
```
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