Only allow renting of available devices

[elYanuki]

• [x] When creating a rent a query should be run that checks if the device is already in use somewhere else.
• [x] The search endpoints should be updated with an aditional arguement wheter you want all or just available
  • [x] this can be nicely by just using the exsting json and providing optional keys
  • [x] the existing searchwithdevicetype method in the device resource should be merged into the search method with the devicetype beeing another queryParam

[Michiii11]

wenn rent abgelehnt wird sollte dieses gerät wieder verfügbar sein oder? nur aktuell verliehene rents sollten verwendet sein

[elYanuki]

Please revise

• [x] the search options should be a DTO in the backend and an interface in the frontend
• the current implementation of the availability check is incredibly weird
  • two speperate implementations exist: one in the Rent repo one in the Device repo
  • i cleaned up the one in the device repo (was mapping to rentDTO and using unnecessary sql
  • [x] please remove the unneeded isDeviceAlreadyInUse method in the rent repo
• [x] the filtering of search results in the device repo is incredibly weird and inefficient - [ ] two ifs check for the same type_id > 0 condition
  • [x] the availabilty check is not included in the sql query but done later on by looping over the result and creating a new query to filter out every singel entry