Fix JS_RUNTIME_HERMES flag definition (#6838)

## Summary

This PR streamlines the definition of the `JS_RUNTIME_HERMES` flag.
Previously, the flag wasn't consistently defined across all usage points
(which prevented the compilation of certain branches of code - for
example in WorkletsModuleProxy.cpp), and it also had duplicated
definitions. Additionally, I've removed outdated and unnecessary checks
from the flag definition.

## Test plan

packages/react-native-reanimated/Common/cpp/worklets/NativeModules/WorkletsModuleProxy.cpp

@@ -7,6 +7,7 @@
 
 #include <worklets/NativeModules/WorkletsModuleProxy.h>
 #include <worklets/SharedItems/Shareables.h>
+#include <worklets/Tools/Defs.h>
 
 #ifdef __ANDROID__
 #include <fbjni/fbjni.h>

packages/react-native-reanimated/Common/cpp/worklets/Tools/Defs.h

@@ -0,0 +1,10 @@
+#pragma once
+
+/*
+On Android JS_RUNTIME_HERMES is set in CMakeList.txt,
+but on iOS there is no simple way to defect if Hermes exists
+so we have to check if headers are available.
+*/
+#if __APPLE__ && __has_include(<hermes/hermes.h>)
+#define JS_RUNTIME_HERMES 1
+#endif

packages/react-native-reanimated/Common/cpp/worklets/WorkletRuntime/ReanimatedHermesRuntime.cpp

@@ -12,12 +12,6 @@
 #include <string>
 #include <utility>
 
-#if __has_include(<reacthermes/HermesExecutorFactory.h>)
-#include <reacthermes/HermesExecutorFactory.h>
-#else // __has_include(<hermes/hermes.h>) || ANDROID
-#include <hermes/hermes.h>
-#endif
-
 namespace worklets {
 
 using namespace facebook;

packages/react-native-reanimated/Common/cpp/worklets/WorkletRuntime/ReanimatedHermesRuntime.h

@@ -1,18 +1,13 @@
 #pragma once
 
-// JS_RUNTIME_HERMES is only set on Android so we have to check __has_include
-// on iOS.
-#if __APPLE__ &&    \
-    (__has_include( \
-        <reacthermes/HermesExecutorFactory.h>) || __has_include(<hermes/hermes.h>))
-#define JS_RUNTIME_HERMES 1
-#endif
+#include <worklets/Tools/Defs.h>
 
 // Only include this file in Hermes-enabled builds as some platforms (like tvOS)
 // don't support hermes and it causes the compilation to fail.
 #if JS_RUNTIME_HERMES
 
 #include <cxxreact/MessageQueueThread.h>
+#include <hermes/hermes.h>
 #include <jsi/decorator.h>
 #include <jsi/jsi.h>
 
@@ -21,12 +16,6 @@
 #include <string>
 #include <thread>
 
-#if __has_include(<reacthermes/HermesExecutorFactory.h>)
-#include <reacthermes/HermesExecutorFactory.h>
-#else // __has_include(<hermes/hermes.h>) || ANDROID
-#include <hermes/hermes.h>
-#endif
-
 #if HERMES_ENABLE_DEBUGGER
 #include <hermes/inspector-modern/chrome/Registration.h>
 #endif // HERMES_ENABLE_DEBUGGER

packages/react-native-reanimated/Common/cpp/worklets/WorkletRuntime/ReanimatedRuntime.cpp

@@ -1,3 +1,4 @@
+#include <worklets/Tools/Defs.h>
 #include <worklets/WorkletRuntime/ReanimatedRuntime.h>
 
 #include <cxxreact/MessageQueueThread.h>

packages/react-native-reanimated/Common/cpp/worklets/WorkletRuntime/ReanimatedRuntime.h

@@ -1,13 +1,5 @@
 #pragma once
 
-// JS_RUNTIME_HERMES is only set on Android so we have to check __has_include
-// on iOS.
-#if __APPLE__ &&    \
-    (__has_include( \
-        <reacthermes/HermesExecutorFactory.h>) || __has_include(<hermes/hermes.h>))
-#define JS_RUNTIME_HERMES 1
-#endif
-
 #include <cxxreact/MessageQueueThread.h>
 #include <jsi/jsi.h>