Move cache for preview to Doctrine Cache

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation
- [ ] StructureSerializer
- [ ] CacheProvider


__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | none
| BC Breaks     | TODO: `temp` in webspace obsolet
| Doc           | none