feat(subplat): add b2b poc

[StaberindeZA]

Proof of Concept - Do Not Merge

Because

• The entitlements service has considered building a business to business feature which would provide access to services without requiring a subscription managed by Stripe.

This pull request

• Adds a proof of concept for a business to business entitlements feature, built for the Mozilla VPN Free Access Program and immediate launch of the feature, while still keeping in mind ongoing development of the entitlements infrastructure as well as allowing for future scalability and extensibility.
• Read list of emails from Strapi and what capabilities should be provided to these users.
• On auth-server /profile query, return the relevant capability if the user email is in the list configured in Strapi.
• Add webhook listener to payments-api that listens for changes in Strapi and then calls an API in auth-server, which broadcasts capability added or removed via event-broker to RPs.
• Show Paid Subscriptions option to user that have access via a B2B subscription. On the subscription management page added a new section indicating services provided by the customers organization.

Issue that this pull request solves

Closes: PAY-3754

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• I have verified that my changes render correctly in RTL (if appropriate).
• I have manually reviewed all AI generated code.

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