[server] fix listAuthProviderDescriptions if unauthenticated

[AlexTugarev]

Description

This is a follow-up from https://github.com/gitpod-io/gitpod/pull/19023/files#r1399425814

Summary generated by Copilot

🤖[deprecated] Generated by Copilot at 84116e8

Add authorization checks to auth provider service API. Use request-context module to get caller identity and context.

Related Issue(s)

Fixes #

How to test

• enable FF for gRPC in server
• see that the Login page is rendered properly

Documentation

Preview status

Gitpod was successfully deployed to your preview environment.

• 🏷️ Name - at-fix-lis0f3e653d7b
• 🔗 URL - at-fix-lis0f3e653d7b.preview.gitpod-dev.com/workspaces.
• 📚 Documentation - See our internal documentation for information on how to interact with your preview environment.
• 📦 Version - at-fix-list-providers-unauthenticated-gha.20417
• 🗒️ Logs - GCP Logs Explorer

Build Options

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Installer

• analytics=segment
• with-dedicated-emulation
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• /werft with-local-preview
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• with-integration-tests=all
  Valid options are all, workspace, webapp, ide, jetbrains, vscode, ssh. If enabled, with-preview and with-large-vm will be enabled.
• with-monitoring

/hold

[geropl]

Change LGTM 👍

[AlexTugarev]

/unhold