DI infrastructure to allow injection of presenters into the timeline.
Add an `@AssistedFactory` of type `TimelineItemPresenterFactory` to a `Presenter` class and bind this factory into the TimelineItemPresenterFactory map multi binding using:
```
@Binds
@IntoMap
@TimelineItemEventContentKey(MyTimelineItemContent::class)
```
A map multibinding of such factories will be available in the `LocalTimelineItemPresenterFactories` composition local for further use down the UI tree.
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