Move hasRole() method from UserInterface to AccountInterface

Problem/Motivation

In #2991232: Add hasRole() method to AccountProxy and UserSession classes we added hasRole() implementation to AccountProxy.php and UserSession.php classes. The AccountInterface remained unchanged to keep it compatible with existing contrib and custom AccountInterface implementations.

Proposed resolution

Move method hasRole() definition to AccountInterface.

Remaining tasks

1. Wait for 10.x branch
2. Wait for #2991232: Add hasRole() method to AccountProxy and UserSession classes to land
3. Do the change
4. Open MR
5. Draft CR: https://www.drupal.org/node/3283218
6. Make sure all tests are still happy
7. Reviews / refinements
8. RTBC

API changes

AccountInterface has been extended with a new method - AccountInterface::hasRole().