Sentry example: add js types to SentryWebpackPluginOptions (#28726)

* Add js types to SentryWebpackPluginOptions

Enables code completion in Visual Studio Code (and perhaps other editors)

* Use partial type for SentryWebpackPluginOptions

This matches the expected type in https://github.com/getsentry/sentry-javascript/blob/e71454ef781563e36c727315d1a5b59acb9e2e0a/packages/nextjs/src/config/webpack.ts#L38

* inline sentry config

examples/with-sentry/next.config.js

@@ -9,16 +9,14 @@ const moduleExports = {
   // Your existing module.exports
 }
 
-const sentryWebpackPluginOptions = {
+// Make sure adding Sentry options is the last code to run before exporting, to
+// ensure that your source maps include changes from all other Webpack plugins
+module.exports = withSentryConfig(moduleExports, {
   // Additional config options for the Sentry Webpack plugin. Keep in mind that
   // the following options are set automatically, and overriding them is not
   // recommended:
   //   release, url, org, project, authToken, configFile, stripPrefix,
   //   urlPrefix, include, ignore
   // For all available options, see:
   // https://github.com/getsentry/sentry-webpack-plugin#options.
-}
-
-// Make sure adding Sentry options is the last code to run before exporting, to
-// ensure that your source maps include changes from all other Webpack plugins
-module.exports = withSentryConfig(moduleExports, sentryWebpackPluginOptions)
+})