Looks up the key with the same bytes as key.
public bool TryGetValue(CosString key, [MaybeNullWhen(false)] scoped out CosObject value)
The key.
The value, resolved one level, when found.
true when the tree holds the key.ISO 32000-2 §7.9.6 and Annex J.3.3: keys are compared byte by byte.