Ensure HTTPS works in the Azure Functions sample

[DamianEdwards]

From comment

[IEvangelist]

Verified locally that HTTPS now works for the Azure Functions sample. Fix in #1691.

Root cause: the local Functions host was only served over HTTP. Adding --useHttps alone fails because the .NET build of Azure Functions Core Tools can't auto-generate a certificate (Auto cert generation is currently not working on the .NET Core build) — it needs an explicit password-protected PFX via --cert/--password.

Fix: --useHttps in the Functions launch profile, plus (run mode only) exporting the trusted ASP.NET Core dev cert with WithHttpsDeveloperCertificate and handing it to the host via WithHttpsCertificateConfiguration (--cert/--password with an ephemeral generated password).

Proof (.NET 10, Aspire 13.4.3, Core Tools 4.12.0, Azurite via Docker):

• Before: curl http://localhost:7221/admin/host/status → 200; HTTPS handshake fails (SEC_E_INVALID_TOKEN).
• After: func host start --port 7221 --useHttps --cert <pfx> --password <generated> listens on :7221.
  • curl https://localhost:7221/admin/host/status without -k → 200 OK {"state":"Running","version":"4.1048..."} — served over HTTPS with the trusted dev cert.
  • Plain http:// to :7221 now fails (HTTPS-only).
  • Frontend serves over HTTPS (200).
  • End-to-end: uploaded a 400x300 image to images → ThumbnailGenerator blob trigger produced a 170x128 thumbnail in thumbnails. Pipeline unaffected.

Closing as resolved; the code change lands in #1691.