Add diagnostic for incorrect `pub (restriction)`

Given the following statement

```rust
pub (a) fn afn() {}
```

Provide the following diagnostic:

```rust
error: incorrect restriction in `pub`
  --> file.rs:15:1
   |
15 | pub (a) fn afn() {}
   | ^^^^^^^
   |
   = help: some valid visibility restrictions are:
           `pub(crate)`: visible only on the current crate
           `pub(super)`: visible only in the current module's parent
           `pub(in path::to::module)`: visible only on the specified path
help: to make this visible only to module `a`, add `in` before the path:
   | pub (in a) fn afn() {}
```

Remove cruft from old `pub(path)` syntax.

0 files changed, 0 insertions, 0 deletions