Remove dependency on global var to detect repo location (DI)

Removes dependency on the global var config.Config to detect location of the repository of storage at the filesystem.
Locator interface includes set of methods from helper package that are used in the services to get location of the repository.
Implementation of the interface needs to be injected into each service that requires it.
In order to break cyclic dependencies some of other funcs was also moved or refactored.

Part of: #2699 (closed)

Implementation with context-scoped injection !2263 (closed)