[core][ios] Use key paths to refer to shared object properties

[tsapeta]

Why

Implementing one of the ideas proposed in #20543

This introduces a syntactic sugar for the following:

Class(MySharedObject.self) {
  Property("foo") { mySharedObject in
    return mySharedObject.foo
  }
}

which could be replaced with the component that takes the key path

Class(MySharedObject.self) {
  Property("foo", \.foo)
}

Moreover, if the property is mutable (var property), it automatically sets the property setter too 🙂

How

• Added two new versions of the Property definition that support Swift key paths (KeyPath for let properties and ReferenceWritableKeyPath for var properties in classes)
• Added native unit tests

Test Plan

It's all green in native unit tests

[Kudo]

nit: would be even better if updating immutable property could have a compiler-time or build-time error. not sure whether it's feasible or not.

[tsapeta]

No, it doesn't seem possible, it's just a JS 🤷‍♂️ We can throw an error at runtime, but the current implementation is the same as in JS. Even Object.defineProperty(obj, "key", { writable: false }) still lets you do the assignment operation, but it's just a no-op and will return undefined when you read that property.

Also, I think it would be nice to add some attributes to the Property, such as writable, enumerable and readonly. The last one is not a part of the descriptor but it could change the behavior so that we throw an error when you try setting that property.

[Kudo]

the Object.defineProperty(obj, "key", { writable: false }) with no-op setter makes sense to me. thanks!

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Suggested change

	- Added support for referencing to `Property`'s owner properties using Swift key paths.
	- Added support for referencing to `Property`'s owner properties using Swift key paths. ([#20610](https://github.com/expo/expo/pull/20610) by [@tsapeta](https://github.com/tsapeta))