Summary:
This diff ended up being a bit more complicated than I anticipated, since the source files in `ReactInternal` were depending on `RCTEventDispatcher`. I made the following changes:
1. Make `RCTEventDispatcher` a `protocol`, keep it in `ReactInternal`.
2. Rename the `RCTEventDispatcher` NativeModule to `RCTEventDispatcherModule`, make it conform to the `RCTEventEmitter` `protocol`, and move it to `CoreModules`.
3. Where necessary, replace categories of `RCTEventDispatcher` with functions.
Changelog:
[iOS][Added] - Make RCTEventDispatcher TurboModule-comaptible
Reviewed By: fkgozali
Differential Revision: D18439488
fbshipit-source-id: b3da15c29459fddf884519f33b0c3b8c036b5539
ea93151f21