Fix prototype chain for non-JsObject prototypes in constructor calls

[Copilot]

The new operator failed to set prototypes correctly when a constructor's prototype was a JsArray or other IJsPropertyAccessor type rather than a JsObject. This broke subclassed array patterns used in Test262 tests.

Changes

• NewExpressionExtensions.cs: Changed prototype type check from is JsObject to is IJsPropertyAccessor to accept any valid JS object-like type as a constructor prototype

// Before: only JsObject prototypes worked
if (TryGetPropertyValue(constructor, "prototype", out var prototype) && prototype is JsObject proto)

// After: JsArray and other IJsPropertyAccessor types work as prototypes
if (TryGetPropertyValue(constructor, "prototype", out var prototype) && prototype is IJsPropertyAccessor)

This enables prototype chain lookups for patterns like:

foo.prototype = new Array(1, 2, 3);
function foo() {}
var f = new foo();
f.every(cb);  // Now correctly finds Array.prototype.every

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Original prompt

run tests from "public class BuiltInsTests : Test262Test" specifically tests where the test method is named "Array_prototype_*"

see what fails, then try to fix those things

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