[Backend Rewrite] Leftover services

[RobbinBaauw]

• Recreate the PreRender service https://github.com/finitum/CSHub/blob/dev/cshub-server/src/endpoints/PreRender.ts
• Recreate a search service. Maybe we can use something like ElasticSearch or https://github.com/valeriansaliou/sonic
• Recreate the email domain service https://github.com/finitum/CSHub/blob/dev/cshub-server/src/endpoints/emaildomains.ts

For all of them: the URLs could have better naming, so feel free to change URLs, HTTP verbs & request/response bodies where you see fit.