fix(rn-tester): use framework-style import for RCTFabricComponentsPlugins.h (#57697)

Summary:
rn-tester's `MyNativeView` example imports `RCTFabricComponentsPlugins.h`. The quoted form resolves under CocoaPods (the bare filename is re-vended via `FACADE_REEXPOSED_HEADERS` in `rncore_facades.rb`) and under the internal Meta build (the per-target header generated by buck's `plugins_header`), but not under SwiftPM. Under SwiftPM the header is exposed as an include directory, so only `<React/RCTFabricComponentsPlugins.h>` resolves. The quoted import makes `MyNativeView` fail to compile when rn-tester is converted to SwiftPM (surfaced by the new SPM CI lane in https://github.com/react/react-native/issues/57659), and switching to the angle form alone would instead break the internal build.

The fix uses a `__has_include` conditional: the angle form when it is available (SwiftPM and CocoaPods) with the quoted form as a fallback (the internal build). This matches the existing pattern in rn-tester's own `NativeCxxModuleExample.h` and keeps all three build stacks compiling.

## Changelog:

[INTERNAL] [FIXED] - Make rn-tester's NativeComponentExample header import resolve under SwiftPM, CocoaPods and the internal build

Pull Request resolved: https://github.com/react/react-native/pull/57697

Test Plan:
- Repro on clean `main`: converting rn-tester to SwiftPM (`spm add --deintegrate`) and building fails at `RNTMyNativeViewComponentView.mm` with `fatal error: 'RCTFabricComponentsPlugins.h' file not found`.
- With this change: the same SwiftPM conversion plus `xcodebuild -configuration Debug -sdk iphonesimulator` gives `BUILD SUCCEEDED`.
- Internal build: `buck2 build fbsource//xplat/js/react-native-github/packages/rn-tester:NativeComponentExampleApple` succeeds (it takes the quoted fallback).
- Existing CocoaPods CI (`test_ios_rntester`) covers the CocoaPods path.

Reviewed By: cipolleschi

Differential Revision: D113771766

Pulled By: fabriziocucci

fbshipit-source-id: e4549508f8e56942b45fa128b2391a290499d4a8

packages/rn-tester/NativeComponentExample/ios/RNTMyNativeViewComponentView.mm

@@ -13,7 +13,11 @@
 #import <react/renderer/components/AppSpecs/Props.h>
 #import <react/renderer/components/AppSpecs/RCTComponentViewHelpers.h>
 
+#if __has_include(<React/RCTFabricComponentsPlugins.h>)
+#import <React/RCTFabricComponentsPlugins.h>
+#else
 #import "RCTFabricComponentsPlugins.h"
+#endif
 
 using namespace facebook::react;