Docs: fix quic stream nullability

[aliyasyeddd]

Description

Corrects the documented nullability of Stream.direction and clarifies that Stream.id returns null only while a stream is pending, not after destruction.

Fix

Updates the doc/api/quic.md descriptions to accurately reflect the current behavior of both properties.

Relation

Fixes #66686

[nodejs-github-bot]

Review requested:

• @nodejs/quic

[github-actions]

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[pimterry]

Hi @aliyasyeddd, thanks for contributing, but I'm afraid there's already an open PR for this: #66687. In future I'd recommend checking for open PRs on issues before opening a new one - if you open the issue you can see the links to other PRs that reference the issue there. It's OK if an old PR has stalled (been left stuck for months) but that's not the case here. I'll close this as a duplicate now.