Rollup merge of #129919 - kevinmehall:waker-getters, r=dtolnay

Stabilize `waker_getters`

Tracking issue: #96992

FCP completed on the tracking issue a while ago. It's not clear whether the libs-api team wanted the `RawWaker` methods moved to `Waker` or went back to the current API after further discussion. `@Amanieu` [wrote "This is just waiting for someone to submit a stabilization PR."](rust-lang/rust#96992 (comment)) so I'm doing just that in hopes of nudging this along.

Edit: Moved the `data` and `vtable` methods from `RawWaker` to `Waker` and added `Waker::new` per rust-lang/rust#96992 (comment)

```rs
impl Waker {
  pub const unsafe fn new(data: *const (), vtable: &'static RawWakerVTable) -> Self;
  pub fn data(&self) -> *const ();
  pub fn vtable(&self) -> &'static RawWakerVTable;
}
```

Closes #96992