Write a function to validate user access rights based on predefined roles.
Implement validate_access(user_roles, role_permissions, requested_permission). user_roles is a list of role names, and role_permissions maps each role to a list of permission names. Return True if at least one assigned role grants the requested permission, otherwise return False. Treat permission and role names as case-sensitive. You may assume every role in user_roles exists in role_permissions.
def validate_access(user_roles, role_permissions, requested_permission):