Allow configuring analyzerMode in bundle-analyzer (#47468)

It's valid to want to output JSON instead of HTML for the bundle
analyzer so we can expose this specific config the same as
`openAnalyzer`. cc @mknichel

packages/next-bundle-analyzer/index.d.ts

@@ -1,8 +1,9 @@
 import type { NextConfig } from 'next'
 
-declare const NextBundleAnalyzer =
-  (options?: { enabled?: boolean; openAnalyzer?: boolean }) =>
-  (config?: NextConfig) =>
-    NextConfig
+declare function NextBundleAnalyzer(options?: {
+  enabled?: boolean
+  openAnalyzer?: boolean
+  analyzerMode?: 'json' | 'static'
+}): (config?: NextConfig) => NextConfig
 
 export = NextBundleAnalyzer

packages/next-bundle-analyzer/index.js

@@ -1,13 +1,13 @@
 module.exports =
-  ({ enabled = true, openAnalyzer = true } = {}) =>
+  ({ enabled = true, openAnalyzer, analyzerMode } = {}) =>
   (nextConfig = {}) => {
     return Object.assign({}, nextConfig, {
       webpack(config, options) {
         if (enabled) {
           const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer')
           config.plugins.push(
             new BundleAnalyzerPlugin({
-              analyzerMode: 'static',
+              analyzerMode: analyzerMode || 'static',
               openAnalyzer,
               reportFilename: !options.nextRuntime
                 ? `./analyze/client.html`