Use SAS emoji data from matrix-doc
Fixes https://github.com/vector-im/element-web/issues/14947
Much like element-web's Jitsi wrapper build steps, this downloads the emoji JSON at build time to ensure it gets reasonably updated. In the future, the spec might want to consider publishing a dedicated i18n package on npm for this, however this is fine for now. We download rather than copy/paste to ensure we always have an updated copy.
