Add token validation filter based on token signature and expiration date

- changed login request from GET to POST
- implement json body conversion to DTO objects
- set `user_id` and `role` attributes for HttpRequest inside filter

src/mock_storage_implementation/UserStorage.cpp

@@ -12,3 +12,8 @@ std::optional<User> MockUserStorage::getUserByUsername(const std::string& userna
 
 	return ret;
 }
+
+bool MockUserStorage::insertUser(const User& user)
+{
+	return true;
+}