[backport] fix: update validation return types (#82854) (#83027)

I updated the return type of API routes and route handlers from

```ts
Promise<Response> | Response | Promise<void> | void
```

to 

```ts
Promise<Response | void> | Response | void
```

which fixes #82842.

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Author: bgub

packages/next/src/server/lib/router-utils/typegen.ts

@@ -549,21 +549,21 @@ export function generateValidatorFile(
 
   if (appRouteHandlerValidations) {
     typeDefinitions += `type RouteHandlerConfig<Route extends AppRouteHandlerRoutes = AppRouteHandlerRoutes> = {
-  GET?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  POST?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  PUT?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  PATCH?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  DELETE?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  HEAD?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
-  OPTIONS?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response> | Response | Promise<void> | void
+  GET?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  POST?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  PUT?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  PATCH?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  DELETE?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  HEAD?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
+  OPTIONS?: (request: NextRequest, context: { params: Promise<ParamMap[Route]> }) => Promise<Response | void> | Response | void
 }
 
 `
   }
 
   if (pagesApiRouteValidations) {
     typeDefinitions += `type ApiRouteConfig = {
-  default: (req: any, res: any) => Promise<void> | void | Promise<Response> | Response
+  default: (req: any, res: any) => Promise<Response | void> | Response | void
   config?: {
     api?: {
       bodyParser?: boolean | { sizeLimit?: string }