Essentially no new code here, just exposing the previously-`pub(crate)` `ValidAlign` type under the name from the ACP.

…ut` methods

Move some tests to more reasonable directories

r? `@petrochenkov`

Add `ptr::Alignment` type

Essentially no new code here, just exposing the previously-`pub(crate)` `ValidAlign` type under the name from the ACP.

ACP: rust-lang/libs-team#108
Tracking Issue: rust-lang#102070

r? `@ghost`

Make tests capture the error printed by a Result return

An error returned by tests previously would get written directly to stderr, instead of to the capture buffer set up by the test harness. This PR makes it write to the capture buffer so that it can be integrated as part of the test output by build tools such as `buck test`, since being able to read the error message returned by a test is pretty critical to debugging why the test failed.

<br>

**Before:**

```rust
// tests/test.rs

#[test]
fn test() -> Result<(), &'static str> {
    println!("STDOUT");
    eprintln!("STDERR");
    Err("RESULT")
}
```

```console
$ cargo build --test test
$ target/debug/deps/test-???????????????? -Z unstable-options --format=json
{ "type": "suite", "event": "started", "test_count": 1 }
{ "type": "test", "event": "started", "name": "test" }
Error: "RESULT"
{ "type": "test", "name": "test", "event": "failed", "stdout": "STDOUT\nSTDERR\n" }
{ "type": "suite", "event": "failed", "passed": 0, "failed": 1, "ignored": 0, "measured": 0, "filtered_out": 0, "exec_time": 0.00040313 }
```

**After:**

```console
$ target/debug/deps/test-???????????????? -Z unstable-options --format=json
{ "type": "suite", "event": "started", "test_count": 1 }
{ "type": "test", "event": "started", "name": "test" }
{ "type": "test", "name": "test", "event": "failed", "stdout": "STDOUT\nSTDERR\nError: \"RESULT\"" }
{ "type": "suite", "event": "failed", "passed": 0, "failed": 1, "ignored": 0, "measured": 0, "filtered_out": 0, "exec_time": 0.000261894 }
```

… r=petrochenkov

Show let-else suggestion on stable.

The E0005 error message has a suggestion to use let-else. Now that let-else is stabilized, I think this message should be included on non-nightly toolchains. I suspect this was just an oversight from rust-lang#93628.  [`E0005.stderr`](https://github.com/ehuss/rust/blob/be1c7aad723126b2ea65543b4ceed54167b841a2/src/test/ui/error-codes/E0005.stderr#L22-L25) contains an example of what this suggestion looks like.

…ind, r=TaKO8Ki

rename `ImplItemKind::TyAlias` to `ImplItemKind::Type`

The naming of this variant seems inconsistent given that this is not really a "type alias", and the associated type variant for `TraitItemKind` is just called `Type`.

… r=jyn514

Don't use unnormalized type in `Ty::fn_sig` call in rustdoc `clean_middle_ty`

Self-explanatory

Fixes rust-lang#102828

…r=jyn514

Remove unnecessary `lift`/`lift_to_tcx` calls from rustdoc

Not sure why they were here in the first place