Rollup merge of #36789 - jseyfried:non_inline_mod_in_block, r=nikomatsakis

Rollup merge of #36789 - jseyfried:non_inline_mod_in_block, r=nikomatsakis

Allow more non-inline modules in blocks

Currently, non-inline modules without a `#[path]` attribute are not allowed in blocks.
This PR allows non-inline modules that have an ancestor module with a `#[path]` attribute, provided there is not a nearer ancestor block.

For example,
```rust
fn main() {
    #[path = "..."] mod foo {
        mod bar; //< allowed by this PR
        fn f() {
            mod bar; //< still an error
        }
    }
}
```

Fixes #36772.
r? @nikomatsakis