Switch unused imports to type imports (graphql#2674)

Author: IvanGoncharov

src/utilities/findDeprecatedUsages.js

@@ -1,6 +1,6 @@
 // @flow strict
 
-import { GraphQLError } from '../error/GraphQLError';
+import type { GraphQLError } from '../error/GraphQLError';
 
 import type { DocumentNode } from '../language/ast';
 

src/utilities/printSchema.js

@@ -9,6 +9,7 @@ import { print } from '../language/printer';
 import { printBlockString } from '../language/blockString';
 
 import type { GraphQLSchema } from '../type/schema';
+import type { GraphQLDirective } from '../type/directives';
 import type {
  GraphQLNamedType,
  GraphQLScalarType,
@@ -21,7 +22,6 @@ import type {
 import { isIntrospectionType } from '../type/introspection';
 import { GraphQLString, isSpecifiedScalarType } from '../type/scalars';
 import {
- GraphQLDirective,
  DEFAULT_DEPRECATION_REASON,
  isSpecifiedDirective,
 } from '../type/directives';