feat(relay): Make relay available for all

[tobias-wilfert]

The managed relay mode is being made available to everyone as such we also need to make the site that is used to configure a managed relay available to everyone.

---

Talked with Vjeran and will try to split this up into its frontend and backend components.

• Frontend: feat(relay): Managed Relay for all (front-end) #98688
• Backend: feat(relay): Managed Relay for all (back-end)  #98696

[github-actions]

🚨 Warning: This pull request contains Frontend and Backend changes!

It's discouraged to make changes to Sentry's Frontend and Backend in a single pull request. The Frontend and Backend are not atomically deployed. If the changes are interdependent of each other, they must be separated into two pull requests and be made forward or backwards compatible, such that the Backend or Frontend can be safely deployed independently.

Have questions? Please ask in the #discuss-dev-infra channel.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
39029	1	39028	607

View the top 1 failed test(s) by shortest run time

tests.sentry.api.endpoints.test_organization_relay_usage.OrganizationRelayHistoryTest::test_endpoint_checks_feature_present

Stack Traces | 1.43s run time

#x1B[1m#x1B[.../api/endpoints/test_organization_relay_usage.py#x1B[0m:87: in test_endpoint_checks_feature_present
    assert resp.status_code == 404
#x1B[1m#x1B[31mE   assert 200 == 404#x1B[0m
#x1B[1m#x1B[31mE    +  where 200 = <Response status_code=200, "application/json">.status_code#x1B[0m

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[tobias-wilfert]

This PR was split into 2 (front-end and back-end) which have since been merged.