Represents a speaker in a TextChannel.
TextSources provide details on permissions users have in
TextChannels. There may be multiple TextSources for a user if
that user belongs in multiple TextChannels.
Create TextSources with TextChannel:AddUserAsync(), which adds
a TextSource to the TextChannel as a descendant.
Remove TextSources by calling TextSource.Destroy.
Name of a TextSource is the Player.DisplayName of the user
associated with the TextSource via TextSource.UserId.
Determines whether the user can send messages to the TextChannel.
UserId of the user represented by the TextSource.
If false, user can only read messages in the TextChannel.
Support for non-user entities may be added in the future via passing in
negative numbers for this property.