Replace WP Scanner for Plugin Check Plugin

[davidperez]

We are currently running a plugin scanner using the WPORG Code Analysis tool:
​https://github.com/wordpress/wporg-code-analysis

The Plugins Team has been working on the Plugin Check Plugin (PCP), and we’re continuously refining it. The tool supports severity levels, which allows us to block a plugin from being approved when we’re confident the issues are not false positives.

My proposal is to replace the current plugin with PCP in update mode.
This will add checks not only related to security, but also to readme standards and WPCS compliance, including deprecated functions.

Finally, I believe we should send the scanner report to plugin authors so they can proactively improve their plugins. Once this change is implemented, we could move forward with the notification system already proposed here: https://meta.trac.wordpress.org/ticket/5637