Feature/con 507 code review updates redo

[tw2113]

This PR handles the following:

1. Continued function/method type declaration and return type declaration.
2. PHP modernization for our supported versions, to simplify code.
3. New API Utility class to create smaller classes and reduce class sizes.
4. Updated API method usage to use Utility class instead of original location.
5. Move deprecated functions to appropriate file.

class-api.php file

The changes for this file are 2 fold.

1. Extraction of utility methods to the new utility class
2. Reorganization of methods to better group together.
   a. Authorization, authentication, api, access/refresh token management functions
   b. get/add/update methods for contacts, lists, etc.

Troubleshooting API stuff was at times hard to follow with associated methods being at opposite ends of the class.

[lindseywb]

LGTM