fix(ios): validate packager messages before parsing

[JoaoPauloCMarra]

Summary:

SocketRocket can deliver binary WebSocket payloads, and RCTJSONParse can return valid JSON fragments. Guard both cases before the iOS dev-support packager connection accesses protocol fields.

Changelog:

[IOS] [FIXED] - Prevent crashes when iOS dev support receives non-object packager messages.

Test Plan:

• Added RNTester unit coverage for binary payloads, non-object JSON, and valid notifications.
• xcodebuild test -workspace RNTesterPods.xcworkspace -scheme RNTester -sdk iphonesimulator -destination "id=25B49671-6960-4F09-AEF7-35E45A0D39CD" -derivedDataPath /tmp/RNTesterBuild -only-testing:RNTesterUnitTests/RCTPackagerConnectionTests
• yarn lint

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