ITextStudioExternalTextSource
public interface ITextStudioExternalTextSourceMarker interface for any component that programmatically drives the text
on a TextStudioText hub (localization bridges, data bindings,
scripted sequences, ...). Enabled components on the same GameObject, or
components explicitly registered with the hub, flip it out of "mirror
TMP.text" mode into "drive TMP.text" mode, so the programmatically-supplied
string wins over whatever a user might have typed into TMP's own text field.
Components that just observe or animate Text Studio do NOT implement this interface - only those that push text content into the hub.