types cleanup (#4409)

Author: ignatiusmb

packages/kit/types/internal.d.ts

@@ -18,7 +18,6 @@ import {
 	RequestOptions,
 	ResolveOptions,
 	ResponseHeaders,
-	RouteSegment,
 	TrailingSlash
 } from './private';
 

packages/kit/types/private.d.ts

@@ -2,8 +2,6 @@
 // but which cannot be imported from `@sveltejs/kit`. Care should
 // be taken to avoid breaking changes when editing this file
 
-import { ValidatedConfig } from './internal';
-
 export interface AdapterEntry {
 	/**
 	 * A string that uniquely identifies an HTTP service (e.g. serverless function) and is used for deduplication.
@@ -191,8 +189,6 @@ export interface Logger {
 
 export type MaybePromise<T> = T | Promise<T>;
 
-export type Only<T, U> = { [P in keyof T]: T[P] } & { [P in Exclude<keyof U, keyof T>]?: never };
-
 export interface Prerendered {
 	pages: Map<
 		string,