Workaround for Flow issue with 'String.raw' (#3080)

In preparation for TS migration

Author: IvanGoncharov

flow-typed/core.js

@@ -1277,7 +1277,7 @@ declare class String {
      * @param callSite A well-formed template string call site representation.
      * @param substitutions A set of substitution values.
      */
-    static raw(callSite: $Shape<{ raw: string, ... }>, ...substitutions: any[]): string;
+    static raw(callSite: string[], ...substitutions: any[]): string; // graphql-js HACK
 }
 
 declare class RegExp {

src/__testUtils__/kitchenSinkQuery.js

@@ -1,4 +1,3 @@
-// $FlowFixMe[incompatible-call]
 export const kitchenSinkQuery: string = String.raw`
 query queryName($foo: ComplexType, $site: Site = MOBILE) @onQuery {
   whoever123is: node(id: [123, 456]) {

src/language/__tests__/printer-test.js

@@ -149,7 +149,6 @@ describe('Printer: Query document', () => {
     expect(JSON.stringify(ast)).to.equal(astBeforePrintCall);
 
     expect(printed).to.equal(
-      // $FlowFixMe[incompatible-call]
       dedentString(String.raw`
       query queryName($foo: ComplexType, $site: Site = MOBILE) @onQuery {
         whoever123is: node(id: [123, 456]) {

src/utilities/__tests__/printSchema-test.js

@@ -157,7 +157,6 @@ describe('Type System Printer', () => {
     });
 
     expectPrintedSchema(schema).to.equal(
-      // $FlowFixMe[incompatible-call]
       dedentString(String.raw`
         type Query {
           singleField(argOne: String = "tes\t de\fault"): String