Rollup merge of #65974 - Centril:matcher-friendly-gating, r=petrochenkov

A scheme for more macro-matcher friendly pre-expansion gating

Pre-expansion gating will now avoid gating macro matchers that did not result in `Success(...)`. That is, the following is now OK despite `box 42` being a valid `expr` and that form being pre-expansion gated:

```rust
macro_rules! m {
    ($e:expr) => { 0 }; // This fails on the input below due to `, foo`.
    (box $e:expr, foo) => { 1 }; // Successful matcher, we should get `2`.
}

fn main() {
    assert_eq!(1, m!(box 42, foo));
}
```

Closes https://github.com/rust-lang/rust/issues/65846.

r? @petrochenkov
cc @Mark-Simulacrum

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