fix(frontend): replace expected-origin-boundary with middleware

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

frontend/src/components/layout/expected-origin-boundary.tsx

@@ -1,37 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-import { headers } from 'next/headers'
-import type { PropsWithChildren } from 'react'
-import React from 'react'
-
-export interface ExpectedOriginBoundaryProps extends PropsWithChildren {
-  expectedOrigin: string
-}
-
-export const buildOriginFromHeaders = (): string | undefined => {
-  const headers1 = headers()
-  const host = headers1.get('x-forwarded-host') ?? headers1.get('host')
-  if (host === null) {
-    return undefined
-  }
-
-  const protocol = headers1.get('x-forwarded-proto')?.split(',')[0] ?? 'http'
-  return `${protocol}://${host}`
-}
-
-export const ExpectedOriginBoundary: React.FC<ExpectedOriginBoundaryProps> = ({ children, expectedOrigin }) => {
-  const currentOrigin = buildOriginFromHeaders()
-
-  if (new URL(expectedOrigin).origin !== currentOrigin) {
-    return (
-      <span
-        className={
-          'text-white bg-dark'
-        }>{`You can't open this page using this URL. For this endpoint "${expectedOrigin}" is expected.`}</span>
-    )
-  }
-  return children
-}