Add more lintable locations to completed-docs rule

[JoshuaKGoldberg]

As per the list by HamletDRC in microsoft/tslint-microsoft-contrib#162, a more complete list of things that could have rules:

• modules
• exported classes
• all classes
• exported interfaces
• interfaces
• interface members
• exported variables
• functions
• exported functions
• public member variables
• all member variables
• public member methods
• all member methods

[Ritzlgrmft]

For me it would be interesting to prevent the check of private properties...