GHA/macos: enable HTTPS tests with stunnel

- Install stunnel.

- Regenerate certificates (as SecureTransport requires a validity period
less than 398 days).

- Restart

GHA/macos: enable HTTPS tests with stunnel

- Install stunnel.

- Regenerate certificates (as SecureTransport requires a validity period
less than 398 days).

- Restart server if it is unresponsive.

- Do not hardcode the SHA-256 base64 public pinned key.

- Ignore test 313 as SecureTransport does not support crl file.

- Ignore tests 1631 and 1632 as SecureTransport is not yet able to shut
down FTP over HTTPS gracefully.

- Add a CMake target for generating certificates.

Closes #14486

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