Merge branch 'service+metrics' of https://github.com/cpp-park-vk-education/2023_1_DDT into service+metrics

# Conflicts:
#	CMakeLists.txt
#	server/CMakeLists.txt
#	server/internal/CMakeLists.txt
#	server/internal/entities/include/Task.hpp
#	server/internal/entities/include/User.hpp
#	server/internal/repository/CMakeLists.txt
#	server/internal/repository/include/SolutionRepository.hpp
#	server/internal/repository/include/TaskRepository.hpp
#	server/internal/repository/src/TaskRepository.cpp
#	server/internal/repository/src/UserRepository.cpp
#	server/internal/repository/virtual/ITaskRepository.hpp
#	server/internal/repository/virtual/IUserRepository.hpp
#	server/internal/service/CMakeLists.txt
#	server/internal/service/include/SolutionService.h
#	server/internal/service/include/TaskService.h
#	server/internal/service/include/UserService.h
#	server/internal/service/include/UserValidator.h
#	server/internal/service/src/SolutionService.cpp
#	server/internal/service/src/TaskService.cpp
#	server/internal/service/src/UserService.cpp
#	server/internal/service/src/UserValidator.cpp
#	server/internal/service/tests/CMakeLists.txt
#	server/internal/service/virtual/ISolutionService.h
#	server/internal/service/virtual/ITaskService.h
#	server/internal/service/virtual/IUserService.h

Entities