feat: export NextFn type helper

Author: thetutlage

src/types/middleware.ts

@@ -10,9 +10,10 @@
 import type { ContainerResolver } from '@adonisjs/fold'
 import type { NextFn } from '@poppinss/middleware/types'
 import type { Constructor, LazyImport } from '@poppinss/utils/types'
-
 import type { HttpContext } from '../http_context/main.ts'
 
+export { NextFn }
+
 /**
  * Middleware represented as a class constructor that implements a handle method
  */