Greetings,

It is my first time trying to contribute to Emacs source code.

The change is adding support for enabling stylistic set (font features)
when using harfbuzz font backend. It is a commonly supported feature in the
editors. See following links

https://code.visualstudio.com/docs/terminal/appearance#_font-feature-settings

https://developer.mozilla.org/en-US/docs/Web/CSS/font-feature-settings

The change adds :font-feature configuration like following

(set-face-attribute 'default nil :font "JetBrains Mono" :height 80
  :font-features '((zero . 1) (ss19 . 0) (calt . 1)))

The render result can be confirmed by adding "0" to composition table

(set-char-table-range composition-function-table
  ?0
  '(["." 0 font-shape-gstring]))

I have read the CONTRIBUTE file and tried to make the commit message as
clear as possible. Please let me know the code review process to get the
patch accepted.


Best,

Binbin