Include user data in message data for non-pinging mentions

[advaith1]

Description
For non-pinging mentions such as mentions in embeds and mentions suppressed with allowed_mentions, they are rendered properly when the user is cached, but otherwise the client just shows the <@id> format or @invalid-user. This is because non-pinging mentions do not include the user data in the mentions array for the message. On the Android app, it seems to always show @invalid-user for mentions suppressed with allowed_mentions, not even attempting to resolve from cache.

Why This is Needed
While allowed_mentions is an official feature, this often breaks mention rendering, which is a major issue if you want to intentionally send non-pinging mentions to see the user's data/profile.

Possible Solutions

• If possible without causing pings, include the user data in the mentions array for non-pinging mentions
• Add a new message property such as other_mentions with data for non-pinging mentions, and use those in rendering

[ghost]

it may be more sensible to pass a "is_notified" flag in each object that is mentioned. If false, treat it as if it didnt mention anyone.

Since v8 isnt default yet, it would be an ideal time to do this as it is semi breaking.

[night]

We have no current plans to extend the message object to include non-mentioned users. While we display in the markdown a user as a mention, we do not parse and store these ignored mentions.