Allow references to uninitialized ambient properties (#36112)

Previously these were incorrectly treated just like normal properties:

```ts
class Parent {
    a: any;
    constructor(arg: any) {
        this.a = arg;
    }
}
class Child extends Parent {
    declare a: number;
    constructor(arg: number) {
        super(arg);
        console.log(this.a);  // Property 'a' is used before being assigned. (2565)
    }
}
```

Fixes #35327

src/compiler/checker.ts

@@ -23298,7 +23298,7 @@ namespace ts {
                 const declaration = prop && prop.valueDeclaration;
                 if (declaration && isInstancePropertyWithoutInitializer(declaration)) {
                     const flowContainer = getControlFlowContainer(node);
-                    if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent) {
+                    if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) {
                         assumeUninitialized = true;
                     }
                 }