ProperEscapingFunctionSniff doesn't catch misuse of wp_json_encode

## Bug Description

[ProperEscapingFunctionSniff](https://github.com/Automattic/VIP-Coding-Standards/blob/54ff2f355aa6bdf5d987636a8e4b817d91e32d5d/WordPressVIPMinimum/Sniffs/Security/ProperEscapingFunctionSniff.php#L20) is a great addition to WPCS. It isn't comprehensive, though.

One specific example that I ran into is that it won't catch improper use of `wp_json_encode()` like it does with other functions.

## Minimal Code Snippet

```html

```

## Error Code

`WordPressVIPMinimum.Security.ProperEscapingFunction`

首先阅读 WordPressVIPMinimum/Sniffs/Security/ProperEscapingFunctionSniff.php，并复现 issue 中最小的 onerror 示例。比较 wp_json_encode 与 esc_html 的处理方式；当误用在该上下文中产生 WordPressVIPMinimum.Security.ProperEscapingFunction 错误时即完成。

由索引模型根据 Issue 内容生成。