[iOS] Remove a stale TODO in State.ts and the unused constants export (#4457)

## Description

Removes two leftovers that reference each other:

- The `TODO use State from RNModule` comment in `src/State.ts`, added in
the TS rewrite (#1327). The idea was to source the `State` object from
the native module's exported constants instead of duplicating the values
in JS. That's no longer viable: the TurboModule spec has no
`getConstants`, web and Jest have no native module to ask, and `as
const` literal types have to exist at compile time anyway.

- The `constantsToExport` method in `RNGestureHandlerModule.mm` (the
`State` and `Direction` dictionaries, exported since 2017) together with
the now-unused `RNGestureHandlerDirection.h` import. Nothing on the JS
side reads these - without `getConstants` in the spec they are
unreachable on the new architecture.

`requiresMainQueueSetup` stays, as module initialization inserts into
the static `_managers` map that component views read on the main thread.

No behavior change.

## Test plan

- Built and ran `basic-example` on the iOS simulator; the app renders
and a tap on the `VirtualGestureDetector` text logs `Tapped on first
part!`.
- Verified nothing references the exported constants: no `getConstants`
in `NativeRNGestureHandlerModule.ts`, no `Module.State` /
`Module.Direction` reads in `src/`.

Author: m-bert

packages/react-native-gesture-handler/apple/RNGestureHandlerModule.mm

@@ -17,7 +17,6 @@
 #import "RNGHRuntimeDecorator.h"
 
 #import "RNGestureHandler.h"
-#import "RNGestureHandlerDirection.h"
 #import "RNGestureHandlerState.h"
 
 #import "RNGestureHandlerButton.h"
@@ -278,28 +277,6 @@ - (void)addOperationBlock:(GestureHandlerOperation)operation
   return @[ @"onGestureHandlerEvent", @"onGestureHandlerStateChange" ];
 }
 
-#pragma mark Module Constants
-
-- (NSDictionary *)constantsToExport
-{
-  return @{
-    @"State" : @{
-      @"UNDETERMINED" : @(RNGestureHandlerStateUndetermined),
-      @"BEGAN" : @(RNGestureHandlerStateBegan),
-      @"ACTIVE" : @(RNGestureHandlerStateActive),
-      @"CANCELLED" : @(RNGestureHandlerStateCancelled),
-      @"FAILED" : @(RNGestureHandlerStateFailed),
-      @"END" : @(RNGestureHandlerStateEnd)
-    },
-    @"Direction" : @{
-      @"RIGHT" : @(RNGestureHandlerDirectionRight),
-      @"LEFT" : @(RNGestureHandlerDirectionLeft),
-      @"UP" : @(RNGestureHandlerDirectionUp),
-      @"DOWN" : @(RNGestureHandlerDirectionDown)
-    }
-  };
-}
-
 - (std::shared_ptr<facebook::react::TurboModule>)getTurboModule:
     (const facebook::react::ObjCTurboModule::InitParams &)params
 {

packages/react-native-gesture-handler/src/State.ts

@@ -1,5 +1,3 @@
-// TODO use State from RNModule
-
 export const State = {
   UNDETERMINED: 0,
   FAILED: 1,