Order Unicode emoji options the same way as web

[gnprice]

In the emoji picker and in emoji autocomplete, Zulip web offers the Unicode emoji in a particular, logical, order. We should match that order.

Implementation

The way this works on web is that a data file groups the emoji by category and has an order within each of the categories, and the code has a list of categories. The data file, like that code, is built into the web client.

See the web implementation in emoji_picker.rebuild_catalog, composebox_typeahead.update_emoji_data which receives its output, and emoji.update_emojis which builds part of its input:
https://github.com/zulip/zulip/blob/0f59e2e78/web/src/emoji_picker.ts#L132-L185
https://github.com/zulip/zulip/blob/0f59e2e78/web/src/composebox_typeahead.ts#L138-L163
https://github.com/zulip/zulip/blob/0f59e2e78/web/src/emoji.ts#L232-L278

So to match that behavior, we'll need that data from the server. This will mean a change to the Zulip server API: there's already an emoji data file we fetch from the server, and it should gain this information. See our [fetchServerEmojiData].