For emoji autocomplete, match insensitively to diacritics

[gnprice]

For emoji autocomplete, if the emoji's name has é where the user's query has e or vice versa, we should treat that as a match. The semantics should match what the web app does.

This doesn't much arise for Unicode emoji, because for all the (small number of) Unicode emoji where a name has a diacritic, we also give the emoji an alternate name by removing the diacritics. It might come up for custom emoji in some realms.

Related issues

• Similar but for @-mentions: autocomplete: In @-mention results, match insensitively to diacritics #237
• Prerequisite: Autocomplete for emoji in message compose #670

[gnprice]

As part of the same work, let's also handle the possibility that the emoji's name has an upper-case letter where the query has lower case.

This one doesn't come up at all for Unicode emoji: all our names are in lower case. But again it might come up for custom emoji in some realms.