[@types/graphql] Add generic type on ExecutionResult (#26763)

* [@types/graphql] Add generic type on ExecutionResult

Without a generic type on ExecutionResult we can't have typesafe
operations.

* Add default type to the generic so it's not a breaking change

* Don't make TData readonly

types/graphql/execution/execute.d.ts

@@ -36,15 +36,19 @@ export interface ExecutionContext {
     errors: GraphQLError[];
 }
 
+export interface ExecutionResultDataDefault {
+    [key: string]: any
+}
+
 /**
  * The result of GraphQL execution.
  *
  *   - `errors` is included when any errors occurred as a non-empty array.
  *   - `data` is the result of a successful execution of the query.
  */
-export interface ExecutionResult {
+export interface ExecutionResult<TData = ExecutionResultDataDefault> {
     errors?: ReadonlyArray<GraphQLError>;
-    data?: { [key: string]: any };
+    data?: TData;
 }
 
 export type ExecutionArgs = {
@@ -69,8 +73,8 @@ export type ExecutionArgs = {
  *
  * Accepts either an object with named arguments, or individual arguments.
  */
-export function execute(args: ExecutionArgs): MaybePromise<ExecutionResult>;
-export function execute(
+export function execute<TData = ExecutionResultDataDefault>(args: ExecutionArgs): MaybePromise<ExecutionResult<TData>>;
+export function execute<TData = ExecutionResultDataDefault>(
     schema: GraphQLSchema,
     document: DocumentNode,
     rootValue?: any,
@@ -78,7 +82,7 @@ export function execute(
     variableValues?: Maybe<{ [key: string]: any }>,
     operationName?: Maybe<string>,
     fieldResolver?: Maybe<GraphQLFieldResolver<any, any>>
-): MaybePromise<ExecutionResult>;
+): MaybePromise<ExecutionResult<TData>>;
 
 /**
  * Given a ResponsePath (found in the `path` entry in the information provided
@@ -89,6 +93,7 @@ export function responsePathAsArray(path: ResponsePath): ReadonlyArray<string |
 /**
  * Given a ResponsePath and a key, return a new ResponsePath containing the
  * new key.
+
  */
 export function addPath(
     prev: ResponsePath | undefined,