Some Unity uids could not be resolved by xrefmap

[filzrev]

On my environment.

<xref:UnityEngine.GameObject> failed to resolve the link.
But <xref:UnityEngine.Behaviour> works as expected.

This seems to be caused by the sort order of xrefmap.yml file.
docfx expecting sorted xrefmap should be sorted by Uid with InvariantCulture string comparer.

But the current contents of xrefmap.json seem to be sorted by other string comparer.
And it causes failure search uid with `BinarySearch'.
https://github.com/dotnet/docfx/blob/7d511fb032de82d0105f08e1f649b2b066697397/src/Docfx.Build/XRefMaps/BasicXRefMapReader.cs#L36