Rollup merge of #126732 - StackOverflowExcept1on:master, r=m-ou-se

Stabilize `PanicInfo::message()` and `PanicMessage`

Resolves #66745

This stabilizes the [`PanicInfo::message()`](https://doc.rust-lang.org/nightly/core/panic/struct.PanicInfo.html#method.message) and [`PanicMessage`](https://doc.rust-lang.org/nightly/core/panic/struct.PanicMessage.html).

Demonstration of [custom panic handler](https://github.com/StackOverflowExcept1on/panicker):
```rust
#![no_std]
#![no_main]

extern crate libc;

#[no_mangle]
extern "C" fn main() -> libc::c_int {
    panic!("I just panic every time");
}

#[panic_handler]
fn my_panic(panic_info: &core::panic::PanicInfo) -> ! {
    use arrayvec::ArrayString;
    use core::fmt::Write;

    let message = panic_info.message();
    let location = panic_info.location().unwrap();

    let mut debug_msg = ArrayString::<1024>::new();
    let _ = write!(&mut debug_msg, "panicked with '{message}' at '{location}'");

    if debug_msg.try_push_str("\0").is_ok() {
        unsafe {
            libc::puts(debug_msg.as_ptr() as *const _);
        }
    }

    unsafe { libc::exit(libc::EXIT_FAILURE) }
}
```
```
$ cargo +stage1 run --release
panicked with 'I just panic every time' at 'src/main.rs:8:5'
```

- [x] FCP: https://github.com/rust-lang/rust/issues/66745#issuecomment-2198143725

r? libs-api

library/std/src/lib.rs

@@ -339,7 +339,6 @@
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_write_slice)]
 #![feature(panic_can_unwind)]
-#![feature(panic_info_message)]
 #![feature(panic_internals)]
 #![feature(pointer_is_aligned_to)]
 #![feature(portable_simd)]