This fixes a pending TODO comment regarding inefficient tags to emojis
mapping, by requiring a full scan over emoji aliases to determine
matches.
Instead, now the JSON file is a map, with aliases as keys, and emojis as
values. The script to convert the file with Python was:
```python
import json
with open("./mailer_emoji.json", "r", encoding="utf-8") as f:
content = json.load(f)
emoji_map = {}
for emoji in content:
for alias in emoji["aliases"]:
if alias in emoji_map:
print("WARNING: Duplicate alias:", alias)
continue
emoji_map[alias] = str(emoji["emoji"])
sorted_emoji_map = {k: emoji_map[k] for k in sorted(emoji_map)}
with open("./mailer_emoji_map.json", "w", encoding="utf-8") as f:
json.dump(sorted_emoji_map, f, indent=4, ensure_ascii=False)
```
