refactor!: switch from LegacyWaffle* to modern waffles (#30330)

This is a first stage for removing the LegacyWaffle* classes.

LegacyWaffleFlag usage replaced with WaffleFlag;
LegacyWaffleSwitche usage replaced with WaffleSwitch;
New CourseWaffleFlag added to the temporary module __future__ as FutureCourseWaffleFlag;
Updated all the imports to use CourseWaffleFlag from the __future__ module;

BREAKING CHANGE: A number of toggle related constants (e.g. ENABLE_ACCESSIBILITY_POLICY_PAGE)
changed types. They were strings, and are now toggle instances (e.g. WaffleSwitch). Although the entire
refactor should be self-contained in edx-platform, if any plugins or dependencies were directly
using these constants, they will break. If this is the case, try to find a better publicized way of
exposing those toggles.

openedx/features/enterprise_support/utils.py

@@ -13,7 +13,7 @@ from django.core.cache import cache
 from django.urls import NoReverseMatch, reverse
 from django.utils.translation import gettext as _
 from edx_django_utils.cache import TieredCache, get_cache_key
-from edx_toggles.toggles import LegacyWaffleFlag
+from edx_toggles.toggles import WaffleFlag
 from enterprise.api.v1.serializers import EnterpriseCustomerBrandingConfigurationSerializer
 from enterprise.models import EnterpriseCustomer, EnterpriseCustomerUser
 from social_django.models import UserSocialAuth
@@ -25,7 +25,7 @@ from openedx.core.djangoapps.site_configuration import helpers as configuration_
 from openedx.core.djangoapps.user_authn.cookies import standard_cookie_settings
 from openedx.core.djangolib.markup import HTML, Text
 
-ENTERPRISE_HEADER_LINKS = LegacyWaffleFlag('enterprise', 'enterprise_header_links', __name__)  # lint-amnesty, pylint: disable=toggle-missing-annotation
+ENTERPRISE_HEADER_LINKS = WaffleFlag('enterprise.enterprise_header_links', __name__)  # lint-amnesty, pylint: disable=toggle-missing-annotation
 
 
 def get_data_consent_share_cache_key(user_id, course_id, enterprise_customer_uuid=None):