Auto merge of #73293 - Aaron1011:feature/macro-rules-arg-capture, r=petrochenkov

Always capture tokens for `macro_rules!` arguments

When we invoke a proc-macro, the `TokenStream` we pass to it may contain 'interpolated' AST fragments, represented by `rustc_ast::token::Nonterminal`. In order to correctly, pass a `Nonterminal` to a proc-macro, we need to have 'captured' its `TokenStream` at the time the AST was parsed.

Currently, we perform this capturing when attributes are present on items and expressions, since we will end up using a `Nonterminal` to pass the item/expr to any proc-macro attributes it is annotated with. However, `Nonterminal`s are also introduced by the expansion of metavariables in `macro_rules!` macros. Since these metavariables may be passed to proc-macros, we need to have tokens available to avoid the need to pretty-print and reparse (see https://github.com/rust-lang/rust/issues/43081).

This PR unconditionally performs token capturing for AST items and expressions that are passed to a `macro_rules!` invocation. We cannot know in advance if captured item/expr will be passed to proc-macro, so this is needed to ensure that tokens will always be available when they are needed.

This ensures that proc-macros will receive tokens with proper `Spans` (both location and hygiene) in more cases. Like all work on https://github.com/rust-lang/rust/issues/43081, this will cause regressions in proc-macros that were relying on receiving tokens with dummy spans.

In this case, Crater revealed only one regression: the [Pear](https://github.com/SergioBenitez/Pear) crate (a helper for [rocket](https://github.com/SergioBenitez/Rocket)), which was previously [fixed](https://github.com/SergioBenitez/Pear/pull/25) as part of https://github.com/rust-lang/rust/pull/73084.

This regression manifests itself as the following error:

```
[INFO] [stdout] error: proc macro panicked
[INFO] [stdout]    --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/rocket_http-0.4.5/src/parse/uri/parser.rs:119:34
[INFO] [stdout]     |
[INFO] [stdout] 119 |             let path_and_query = pear_try!(path_and_query(is_pchar));
[INFO] [stdout]     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = help: message: called `Option::unwrap()` on a `None` value
[INFO] [stdout]     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
```

It can be fixed by running `cargo update -p pear`, which updates your `Cargo.lock` to use the latest version of Pear (which includes a bugfix for the regression).

Split out from https://github.com/rust-lang/rust/pull/73084/

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