SSO/logistration: lazy‑load third_party_auth_context to break import cycle

[subhashree-sahu31]

PR Description
This PR fixes a circular import issue affecting enterprise SSO/authn context generation.

Problem

• openedx/features/enterprise_support/utils.py imported third_party_auth_context at module load time from openedx/core/djangoapps/user_authn/views/utils.py.
• That authn utils module also depends on enterprise utilities, creating a circular import path in certain load orders.

Root Cause
A top-level cross-module import between enterprise_support.utils and user_authn.views.utils caused Python to initialize partially loaded modules, which can break org-name/SSO context resolution flows.

Fix

• Removed the top-level import of third_party_auth_context from enterprise_support.utils.
• Added a function-scoped import inside get_mfe_context():
• from openedx.core.djangoapps.user_authn.views.utils import third_party_auth_context
• This preserves existing behavior while deferring the import until runtime, avoiding circular module initialization.

Why this is safe

• No functional logic changes to auth flow, provider selection, or enterprise branding payload.
• Same helper is used with the same arguments; only import timing changed.
• Pattern is consistent with existing lazy imports in enterprise/authn code for circular dependency prevention.

Impact

• Prevents circular import failures in enterprise-authn context assembly.
• Reduces risk of intermittent SSO login context issues related to module import order.
• No API contract changes.

Testing / Validation

• Verified get_mfe_context() still builds:
• third_party_auth_context
• countryCode
• enterpriseBranding (when enterprise customer is present)

Suggested regression checks:

• Enterprise login page load with org flow
• TPA hinted login (tpa_hint) flow
• Non-enterprise login flow
• Authn MFE context endpoint response shape unchanged

JIRA
https://2u-internal.atlassian.net/browse/AUT-112

[Copilot]

Pull request overview

This PR addresses a circular import affecting enterprise SSO/authn context generation by deferring an import until get_mfe_context() runtime, reducing the chance of partially initialized modules during certain import orders.

Changes:

• Removed the module-level import of third_party_auth_context from enterprise_support.utils.
• Added a function-scoped import of third_party_auth_context inside get_mfe_context() to break the circular dependency at import time.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[pwnage101]

Approving to unblock, but I really don't like where this landed.

[pwnage101]

I'm really not a fan of #139 introducing a duplicate get_mfe_context definition. Now we just have two identical get_mfe_context functions defined in different modules, independently tested, and each lazily imports modules from functions in each other's module. Very messy.