Make it possible to have finer control over font substitution

Currently font substitution is done purely on family name, so if that family does not exist then it falls back to another family. What is requested is that it takes the style name into account as well, so if the family + style does not exist then it is possible to provide a different substitution to fall back to a different family + style. For example:

If Noto Sans with Condensed Black does not exist then it could be substituted with Noto Sans CJK JP with Black.