split user functions into access & registration

[github-actions[bot]]

https://github.com/StruckCroissant/Game-DB/blob/ea534febc7dc7b7df03b89e2768044d061ecd26c/api/main/java/com/StruckCroissant/GameDB/api/user/UserController.java#L40

        return response;
    }

    // TODO split user functions into access & registration
    @PostMapping("/register")
    public String registerUser(@RequestBody UserRegistrationRequest request){
        return userService.registerUser(request);

[StruckCroissant]

commit cddca91 developed split further - needs to be finalized & tested

[StruckCroissant]

Split not needed. Spring Security handles user login & the registration controller handles the user signup process. Removed previous login functionalities left in User Controller/Service 256abf0