Auto merge of #130157 - eduardosm:stabilize-const_float_classify, r=RalfJung

Stabilize `const_float_classify`

Tracking issue: rust-lang/rust#72505

Also reverts rust-lang/rust#114486

Closes rust-lang/rust#72505

Stabilized const API:

```rust
impl f32 {
    pub const fn is_nan(self) -> bool;
    pub const fn is_infinite(self) -> bool;
    pub const fn is_finite(self) -> bool;
    pub const fn is_subnormal(self) -> bool;
    pub const fn is_normal(self) -> bool;
    pub const fn classify(self) -> FpCategory;
    pub const fn is_sign_positive(self) -> bool;
    pub const fn is_sign_negative(self) -> bool;
}

impl f64 {
    pub const fn is_nan(self) -> bool;
    pub const fn is_infinite(self) -> bool;
    pub const fn is_finite(self) -> bool;
    pub const fn is_subnormal(self) -> bool;
    pub const fn is_normal(self) -> bool;
    pub const fn classify(self) -> FpCategory;
    pub const fn is_sign_positive(self) -> bool;
    pub const fn is_sign_negative(self) -> bool;
}
```

cc `@rust-lang/wg-const-eval` `@rust-lang/libs-api`

Author: bors