* Add phpstan

* Move top-level functions to Api.php

* Move getVersion to Api file

* Rename Api.php to functions.php

* Add function files to composer autoload

* Organize the loader file

* Add phpstan config

* Fix phpstan warnings

* Downgrade circleci config to 7.2 to match composer

* Add phpstan to circleci

* Add inferPrivatePropertyTypeFromConstructor to phpstan config