Deprecate the unstable `ptr_to_from_bits` feature
I propose that we deprecate the (unstable!) `to_bits` and `from_bits` methods on raw pointers. (With the intent to ~~remove them once `addr` has been around long enough to make the transition easy on people -- maybe another 6 weeks~~ remove them fairly soon after, as the strict and expose versions have been around for a while already.)
The APIs that came from the strict provenance explorations (#95228) are a more holistic version of these, and things like `.expose_addr()` work for the "that cast looks sketchy" case even if the full strict provenance stuff never happens. (As a bonus, `addr` is even shorter than `to_bits`, though it is only applicable if people can use full strict provenance! `addr` is *not* a direct replacement for `to_bits`.) So I think it's fine to move away from the `{to|from}_bits` methods, and encourage the others instead.
That also resolves the worry that was brought up (I forget where) that `q.to_bits()` and `(*q).to_bits()` both work if `q` is a pointer-to-floating-point, as they also have a `to_bits` method.
Tracking issue #91126
Code search: https://github.com/search?l=Rust&p=1&q=ptr_to_from_bits&type=Code
For potential pushback, some users in case they want to chime in
- `@RSSchermer` 365bb68541/arwa/src/html/custom_element.rs (L105)
- `@strax` 99616d1dbf/openexr/src/core/alloc.rs (L36)
- `@MiSawa` 577c622358/crates/kernel/src/timer.rs (L50)
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