feat: allow passing down "null" to disable server watcher (#14208)

Co-authored-by: Bjorn Lu <[email protected]>

Author: sheremet-va

config/server-options.md

@@ -176,7 +176,7 @@ The error that appears in the Browser when the fallback happens can be ignored.
 
 ## server.watch
 
-- **Type:** `object`
+- **Type:** `object | null`
 
 File system watcher options to pass on to [chokidar](https://github.com/paulmillr/chokidar#api).
 
@@ -197,6 +197,8 @@ export default defineConfig({
 })
 ```
 
+If set to `null`, no files will be watched. `server.watcher` will provide a compatible event emitter, but calling `add` or `unwatch` will have no effect.
+
 ::: warning Using Vite on Windows Subsystem for Linux (WSL) 2
 
 When running Vite on WSL2, file system watching does not work when a file is edited by Windows applications (non-WSL2 process). This is due to [a WSL2 limitation](https://github.com/microsoft/WSL/issues/4739). This also applies to running on Docker with a WSL2 backend.

guide/api-javascript.md

@@ -75,7 +75,8 @@ interface ViteDevServer {
    */
   httpServer: http.Server | null
   /**
-   * Chokidar watcher instance.
+   * Chokidar watcher instance. If `config.server.watch` is set to `null`,
+   * returns a noop event emitter.
    * https://github.com/paulmillr/chokidar#api
    */
   watcher: FSWatcher