[Platform] Adding token usage / consumption in `DeferredResult` when using platforms

[Guikingone]

See #416

Wouldn't it make sense to group this data into a DTO, like there is TokenUsage, and then add that DTO to metadata or perhaps even reuse the said DTO?

Originally posted by @junaidbinfarooq in #416 (comment)

[OskarStark]

@Guikingone will you tackle this issue?

[Guikingone]

Yes, already on it.