Disable strictExportPresence when webpack 5 is enabled

Solves an issue some users ran into where enabling webpack 5 highlighted a wrong JSON import where named exports were used for JSON data.

> Should not import the named export 'myValue' (imported as 'myValue') from default-exporting module (only default export is available soon)

packages/next/build/webpack/config/blocks/base.ts

@@ -1,6 +1,6 @@
 import isWslBoolean from 'next/dist/compiled/is-wsl'
 import curry from 'next/dist/compiled/lodash.curry'
-import { webpack } from 'next/dist/compiled/webpack/webpack'
+import { webpack, isWebpack5 } from 'next/dist/compiled/webpack/webpack'
 import { ConfigurationContext } from '../utils'
 
 const isWindows = process.platform === 'win32' || isWslBoolean
@@ -46,7 +46,9 @@ export const base = curry(function base(
   if (!config.module) {
     config.module = { rules: [] }
   }
-  config.module.strictExportPresence = true
+
+  // TODO: add codemod for "Should not import the named export" with JSON files
+  config.module.strictExportPresence = !isWebpack5
 
   return config
 })