[New Rule] Implement sniff for class properties PHPDoc formatting

[lenaorobei]

Rule

PHPDoc formatting for class properties.

Acceptance Criteria:

• Sniff covers described on DevDocs requirements:

Class attributes must have type declaration using @var tag.

• Rule covered by unit test.

<severity>5</severity>
<type>warning</type>

[lenaorobei]

Hi @ryantfowler! How is your progress with this ticket? Do you need any help?