workaround rust-analyzer bug

Summary:
Somehow this `use *` was confusing rust-analyzer to mix up `syntax::Argument` and `schema::Argument` in other places.

No need to use `*` for just 2 types anyway, so switching to the explicit `use`.

Reviewed By: alunyov

Differential Revision: D33371613

fbshipit-source-id: 05d12d973309b7110953c5cf8ca370c322fb30b5

Author: kassens

compiler/crates/schema/src/definitions.rs

@@ -6,7 +6,7 @@
  */
 
 use common::{Named, NamedItem, WithLocation};
-use graphql_syntax::*;
+use graphql_syntax::{ConstantValue, DirectiveLocation};
 use intern::string_key::{Intern, StringKey};
 use lazy_static::lazy_static;
 use std::collections::HashMap;