Issue 4868/2: Add limited embedding support for OTC fonts

Issue 4868/2: Add limited embedding support for OTC fonts

This commit adds limited embedding support
for OpenType/CFF Collection (OTC) fonts
which have `*.otc' filename extension.

Essentially, the extension of OTC font files should be `*.otc'.
However, most of the OTC fonts have the extension `*.ttc'
for backward compatibility.
https://www.microsoft.com/typography/otspec/recom.htm

So this is limited support
because most of the OTC fonts cannot be used.

TODO: distinguish files which have extension `*.ttc'
whether TrueType Collection (TTC) fonts or OTC fonts.