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`