PHP Coding standards fine-tuning

[reimic]

With coding standards implemented and linting on the way, it is to be considered if this library should apply all WordPress coding standards.

Some of the prompts to consider:

phpcs: File operations should use WP_Filesystem methods instead of direct PHP filesystem calls.

(This library has no direct access to WordPress. And for good reason.)

phpcs: Missing doc comment for function testUnzipFileWhenUsingAbsolutePath()

(Expects docs for every test.)

phpcs: Missing short description in doc comment

(Expects description for every doc.)

phpcs: Missing @throws tag in function comment

… and more.

[adamziel]

phpcs: Missing @throws tag in function comment

This one sounds useful, the rest I'd disable for now. Good call. Let's pick and choose the rules that are the most useful and fine-tune them as we go.