Merge #2179

2179: Use HirDatabase to compute `is_deprecated` r=matklad a=martskins

This PR fixes #2167 by introducing `attributes_query` and adding `fn attrs(&self, def: crate::AttrDef) -> Option<Arc<[Attr]>>;`  to the `DefDatabase` trait.

I'm a little concerned about the two spots in `attributes_query` where code is repeated, but I couldn't figure out a way to avoid that, so.. I welcome suggestions 😄 



Co-authored-by: Martin Asquino <martin.asquino@gmail.com>

crates/ra_hir/src/lib.rs

@@ -61,6 +61,7 @@ use crate::{ids::MacroFileKind, resolve::Resolver};
 pub use crate::{
     adt::VariantDef,
     code_model::{
+        attrs::{AttrDef, Attrs},
         docs::{DocDef, Docs, Documentation},
         src::{HasBodySource, HasSource},
         Adt, AssocItem, Const, ConstData, Container, Crate, CrateDependency, DefWithBody, Enum,