Ligature fonts installed on system

I manually installed two fonts on my system: “SF Mono” and “Liga SF Mono”, which is just “SF Mono” with Fira’s ligatures added with [this tool](https://github.com/ToxicFrog/Ligaturizer). In the “Fonts” menu “SF Mono” shows up by itself, but Liga SF Mono does not. This is probably due to iOS not recognizing as monospaced, because some of the ligatures are double or triple width. A lot of other apps have the same issue. [Textastic 9](https://twitter.com/textastic/status/1225470379902341121?s=21) for example fixes this issue for that app (maybe the developer can help?).

I managed to add in “Liga SF Mono” by adding a new font with a custom Stylesheet, for which I had to host [a private gist on GitHub](https://gist.github.com/Kamik423/072b6775b894412547afb384ce05d4c8):

```css
@font-face {
font-family: "Liga SF Mono";
src: local("Liga SF Mono");
}
```

I have never used css `@font-face`s before. It took me too long to get it working with a local font. You shouldn’t be expecting this from everyone. This cannot be the best way to do this. Please allow the user to either choose from any font or build a system to include locally installed ligature fonts without jumping through all those hoops.

**EDIT:** First I tried using Pastebin and Hastebin, but their raw urls don’t end in `.css`, so blink does not accept them.

Start with the iOS Fonts menu and the custom Stylesheet path described in the issue, reproducing the problem with locally installed SF Mono and Liga SF Mono. Compare the existing @font-face workaround with the requested behavior; done means users can select locally installed ligature fonts without hosting a CSS file.

Written by the indexing model from the issue text.