Add eslint config options to NextConfig type (vercel#27446)

This adds missing eslint config options to the public `NextConfig` type.

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes

packages/next/server/config-shared.ts

@@ -22,9 +22,18 @@ export interface DomainLocale {
   locales?: string[]
 }
 
+export interface ESLintConfig {
+  /** Only run ESLint on these directories during production builds (`next build`). */
+  dirs?: string[]
+  /** Do not run ESLint during production builds (`next build`). */
+  ignoreDuringBuilds?: boolean
+}
+
 export type NextConfig = { [key: string]: any } & {
   i18n?: I18NConfig | null
 
+  eslint?: ESLintConfig
+
   headers?: () => Promise<Header[]>
   rewrites?: () => Promise<
     | Rewrite[]