Flag if Advanced Custom Fields plugin version is 4.*

## Describe the solution you'd like

On https://docs.wpvip.com/technical-references/plugins/acf-5-and-vip-go/, we prohibit using any ACF version 4:

> Please note that while ACF version 5 can be used on most VIP Go sites (at customer discretion), ACF 4 should not be used.

## What code should be reported as a violation?

```
/*
Plugin Name: Advanced Custom Fields
Plugin URI: http://www.advancedcustomfields.com/
Description: Customise WordPress with powerful, professional and intuitive fields
Version: 4.4.4
Author: Elliot Condon
Author URI: https://www.advancedcustomfields.com
Text Domain: acf
Domain Path: /lang
*/

```

```
/*
Plugin Name: Advanced Custom Fields PRO
Plugin URI: http://www.advancedcustomfields.com/
Description: Customise WordPress with powerful, professional and intuitive fields
Version: 4.4.4
Author: Elliot Condon
Author URI: https://www.advancedcustomfields.com
Text Domain: acf
Domain Path: /lang
*/

```

## What code should *not* be reported as a violation?

```
/*
Plugin Name: Advanced Custom Fields
Plugin URI: https://www.advancedcustomfields.com
Description: Customize WordPress with powerful, professional and intuitive fields.
Version: 5.9.5
Author: Elliot Condon
Author URI: https://www.advancedcustomfields.com
Text Domain: acf
Domain Path: /lang
*/
```

```
/*
Plugin Name: Advanced Custom Fields PRO
Plugin URI: https://www.advancedcustomfields.com
Description: Customize WordPress with powerful, professional and intuitive fields.
Version: 5.9.5
Author: Elliot Condon
Author URI: https://www.advancedcustomfields.com
Text Domain: acf
Domain Path: /lang
*/

```

Locate the existing plugin-header and version checks and their tests, then compare them with the ACF 4.4.4 and 5.9.5 examples in this issue. Done means ACF and ACF PRO version 4.* are reported as violations while version 5.* is not, with tests covering both cases.

Written by the indexing model from the issue text.