Rollup merge of #37084 - jseyfried:cleanup_expanded_macro_use_scopes, r=nrc

Rollup merge of #37084 - jseyfried:cleanup_expanded_macro_use_scopes, r=nrc

macros: clean up scopes of expanded `#[macro_use]` imports

This PR changes the scope of macro-expanded `#[macro_use]` imports to match that of unexpanded `#[macro_use]` imports. For example, this would be allowed:
```rust
example!();
macro_rules! m { () => { #[macro_use(example)] extern crate example_crate; } }
m!();
```

This PR also enforces the full shadowing restrictions from RFC 1560 on `#[macro_use]` imports (currently, we only enforce the weakened restrictions from #36767).

This is a [breaking-change], but I believe it is highly unlikely to cause breakage in practice.
r? @nrc