[BUG][builtin] Fixed Array flat implementation

### 发生了什么问题？

Fixed Array flat implementation

### 期望行为是什么？

Fixed Array flat implementation

### 如何复现该缺陷

```
const arr = new Array<Any>(1, [1, [1, undefined ,2], 2], 3)

console.log(JSON.stringify(arr.flat(2)))

const arr1 = [0, 1, 2, [3, 4]];

console.log(JSON.stringify(arr1.flat()));
// expected output: Array [0, 1, 2, 3, 4]

const arr2 = [0, 1, [2, [3, [4, 5]]]];

console.log(JSON.stringify(arr2.flat()));
// expected output: Array [0, 1, 2, Array [3, Array [4, 5]]]

console.log(JSON.stringify(arr2.flat(2)));
// expected output: Array [0, 1, 2, 3, Array [4, 5]]

console.log(JSON.stringify(arr2.flat(Infinity)));
// expected output: Array [0, 1, 2, 3, 4, 5]

const arr4 = [1, 2, 1];

const result = arr4.flatMap((num) => (num === 2 ? [[2, 2], 2] : 1));

console.log(JSON.stringify(result));

const arr5 = [1, undefined, 1];

const result2 = arr5.flatMap((num) => (num === 2 ? [2, 2] : 1));

console.log(JSON.stringify(result2));
// Expected output: Array [1, 2, 2, 1]

```

### 其他补充信息

### 版本或分支信息

- [ ] master
- [ ] 5.1-Release
- [ ] 5.0-Release
- [x] 5.0-Beta1
- [ ] Release 4.1
- [ ] Release 4.0
- [ ] Release 3.2

OpenHarmony/arkcompiler_runtime_core
Closed