Move business logic from User Controller to User Service

[pbn4]

Currently business logic for User module is spread across controller and service, which by convention should not be the case. Example:

  async create(
    @Body() dto: UserCreateDto,
    @Query() queryParams: UserCreateQueryParams
  ): Promise<UserBasicDto> {
    const user = await this.userService.createUser(dto)
    if (!queryParams.noWelcomeEmail) {
      await this.emailService.welcome(user, dto.appUrl)
    }
    return mapTo(UserBasicDto, user)
  }

sending welcome emails should be encapsulated within User service.