9681: Respect `#[doc(hidden)]` in dot-completion r=jonas-schievink a=jonas-schievink
This adds `CompletionContext::is_visible` as a convenience method that checks visibility, presence of `doc(hidden)`, and whether the completed item is in the same crate as the completion site or not. We only complete `doc(hidden)` items from the same crate.
This doesn't yet work for *all* completions: `qualified_path` completions use `Module::scope` and `ScopeDef`, which doesn't work with this.
Part of https://github.com/rust-analyzer/rust-analyzer/issues/7718
Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>