better names for `[GET] /workspace/ws_id/files`'s return type's properties.. `size` instead of `filesize` etc.

add info field to GetFileResponseData interface and display the the additional useful data it can contain

added ApiError instead of number as error result of all backend.services; added throwError to cancel loading of units

first successful run after merging tc + admin; workspace monitor extracted from admin; testcontroller works; syscheck does not work; admin login failed

* problem: interceptor in workspace module ignored!

* response type json removed
* logout removed
* optical markers deleted