Fix/coupling issues stage 1

[titpetric]

• all: moved repository and service packages under service/internal
• updated imports,
• created new system/service public API for User and Rules
  • before: UserService.With(ctx) UserService (interface), after: User(ctx) UserService (global)

Compile for all services works. The system-cli package is broken, due to using repository. I'd suggest creating service specific cli functions under service/cli/ExecUsersMerge(), ...