Automate API documentation

[jonasraoni]

Describe the bug
Once the #7698 is complete, we should replace the current API documentation approach (see https://github.com/pkp/pkp-lib/blob/3a8efd4f8b8fd195e13c46542d7785e158f947e9/tools/buildSwagger.php) by something more automated, probably based on PHPDoc/annotations.

The current documentation also doesn't honor the user expectations (see #8945).

Benefits:

• With the documentation living closer to the code, it will be easier to keep it synchronized.
• An automated tool will make it easier to upgrade from "Swagger v2" to a newer version.
• Perhaps the same documentation can be used to generate other formats (e.g. Postman collections).

Options
At this moment, this seems to be by far the most popular Laravel based project: https://github.com/DarkaOnLine/L5-Swagger, perhaps the scenario will be different later.