Replace rustc_data_structures::thin_vec::ThinVec with thin_vec::ThinVec.

`rustc_data_structures::thin_vec::ThinVec` looks like this:
```
pub struct ThinVec<T>(Option<Box<Vec<T>>>);
```
It's just a zero word if the vector is empty, but requires two
allocations if it is non-empty. So it's only usable in cases where the
vector is empty most of the time.

This commit removes it in favour of `thin_vec::ThinVec`, which is also
word-sized, but stores the length and capacity in the same allocation as
the elements. It's good in a wider variety of situation, e.g. in enum
variants where the vector is usually/always non-empty.

The commit also:
- Sorts some `Cargo.toml` dependency lists, to make additions easier.
- Sorts some `use` item lists, to make additions easier.
- Changes `clean_trait_ref_with_bindings` to take a
  `ThinVec<TypeBinding>` rather than a `&[TypeBinding]`, because this
  avoid some unnecessary allocations.

compiler/rustc_parse/src/parser/attr_wrapper.rs

@@ -355,7 +355,7 @@ impl<'a> Parser<'a> {
             && matches!(self.capture_state.capturing, Capturing::Yes)
             && has_cfg_or_cfg_attr(final_attrs)
         {
-            let attr_data = AttributesData { attrs: final_attrs.to_vec().into(), tokens };
+            let attr_data = AttributesData { attrs: final_attrs.iter().cloned().collect(), tokens };
 
             // Replace the entire AST node that we just parsed, including attributes,
             // with a `FlatToken::AttrTarget`. If this AST node is inside an item