improves baseUrl resolution in typescript monorepos

Typescript configuration can inherit from files above cwd in the
filesystem. If a baseUrl was declared in such a file, it would not be
picked up by the webpack config. This would force users to use the
next-transpile-module and duplicate configuration with unintuitive path
relations (see vercel#13197 for a detailed analysis)

If baseUrl is resolved it should be used instead of dir as the root
include for babel-resolve-loader.

An even nicer DX would auto detect the presence of a `paths` section in
the typescript config and automatically include
`tsconfig-paths-webpack-plugin`

packages/next/build/webpack-config.ts

@@ -52,6 +52,11 @@ import WebpackConformancePlugin, {
 } from './webpack/plugins/webpack-conformance-plugin'
 import { WellKnownErrorsPlugin } from './webpack/plugins/wellknown-errors-plugin'
 import { codeFrameColumns } from '@babel/code-frame'
+import { getTypeScriptConfiguration } from '../lib/typescript/getTypeScriptConfiguration'
+import {
+  NecessaryDependencies,
+  hasNecessaryDependencies,
+} from '../lib/typescript/hasNecessaryDependencies'
 
 type ExcludesFalse = <T>(x: T | false) => x is T
 
@@ -250,7 +255,18 @@ export default async function getBaseWebpackConfig(
   let jsConfig
   // jsconfig is a subset of tsconfig
   if (useTypeScript) {
-    jsConfig = parseJsonFile(tsConfigPath)
+    // Ensure TypeScript and necessary `@types/*` are installed:
+    const deps: NecessaryDependencies = await hasNecessaryDependencies(dir)
+
+    // Load TypeScript after we're sure it exists:
+    const ts = (await import(
+      deps.resolvedTypeScript
+    )) as typeof import('typescript')
+    const tsConfig: import('typescript').ParsedCommandLine = await getTypeScriptConfiguration(
+      ts,
+      tsConfigPath
+    )
+    jsConfig = { compilerOptions: tsConfig.options }
   }
 
   const jsConfigPath = path.join(dir, 'jsconfig.json')
@@ -760,7 +776,9 @@ export default async function getBaseWebpackConfig(
       rules: [
         {
           test: /\.(tsx|ts|js|mjs|jsx)$/,
-          include: [dir, ...babelIncludeRegexes],
+          include: resolvedBaseUrl
+            ? [resolvedBaseUrl, ...babelIncludeRegexes]
+            : [dir, ...babelIncludeRegexes],
           exclude: (path: string) => {
             if (babelIncludeRegexes.some((r) => r.test(path))) {
               return false