This mostly moves code from server_events_dispatch, but
it also de-duplicates the logic in emoji_success(), and
it does early-return for the "text" case to keep the
function a bit flatter.
We no longer have a special UI setting and model
field ("emoji_alt_code") for saying users want text-only
emojis. We now instead make "text" be a fifth choice
for "emojiset".
Fixes#7406
For setting the night mode, it checks to see if you’re in development
by checking `page_params.development`, but the actual attribute is
`page_params.development_environment`.
We should use variables in i18n strings to give proper context to the
translators. If the pattern is this:
```
i18n.t("Count " + count + " items")
```
Then it will be captured like this:
```
{"Count" + count + "items": ""}
```
Which is not good for the translators.
Note that this code is disabled until the infrastructure for the
feature can be finished.
Tweaked by tabbott to use slightly cleaner names for the various sets.