LaTeX and PDF exports fail when italic or bold-italic variants of greek characters are included

Currently, Manuscripts (and therefore Pressroom) only handles regular variants of greek characters when exporting to LaTeX or PDF when using unicode-to-latex.json.

In initial testing, it seems italic and bold-italic variants are not handled. E.g. θ is handled, but 𝜃 and 𝜽 are not handled.