WPCS 2.0: Migrate Deprecated VIP Sniffs

[tomjn]

WPCS 1.0.0 deprecates VIP sniffs, with the intention that they be removed in a later release. We should copy these sniffs to VIP Minimum appropriatley so that our own sniffs and rules aren't broken by a future release

[GaryJones]

All but one of the WordPressVIPMinimum/Sniffs implement a core PHPCS sniff (PHP_CodeSniffer_Sniff currently, but will be PHP_CodeSniffer\Sniffs\Sniff if #190 happens first). There is no dependency on WPCS here.

The other Sniff, DeclarationCompatibilitySniff, extends \PHP_CodeSniffer_Standards_AbstractScopeSniff. There is no dependency on WPCS here.

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Our ruleset.xml files contain references to WordPress.VIP, which need to be removed. See #298.

[GaryJones]

All but one of the WordPressVIPMinimum/Sniffs implement a core PHPCS sniff

Correction - there are three classes in WordPressVIPMinimum/Sniffs/VIP that extend WPCS classes directly.

[GaryJones]

WPCS has just removed the VIP sniffs from it's develop branch, with the aim to push this out as a WPCS 2.0.0 soon.

As such, we should finish off the migration of the WordPress.VIP sniffs, and check our dependency constraints (constraint is "1.*", so we're fine here).