#2185941 Converted user_page() to a new style controller

from: 'fn:user_login_form'
to: \Drupal\user\Form\UserLoginForm
from: 'fn:user_page'
to: '\Drupal\user\Controller\UserController::userPage'
from: 'fn:user_login_name_validate'
to: '\Drupal\user\Form\UserLoginForm::validateName'
from: 'fn:user_login_authenticate_validate'
to: '\Drupal\user\Form\UserLoginForm::validateAuthentication'
from: 'fn:user_login_final_validate'
to: '\Drupal\user\Form\UserLoginForm::validateFinal'
from: 'fn:user_login_finalize'
to: 'fn:user_login_finalize'