Add a few more plugins that blocks XML-RPC

[crazytonyli]

Relates to wordpress-mobile/WordPress-iOS#25183

The new plugins and new xmlrpc_blocking_plugins API will be used in the app to show what plugins may blocked the site's XML-RPC endpoint.

[jkmassel]

I'm not sure how this should work – the application blocking plugins can be detected by fetching the JSON API root, but these XMLRPC ones would only be detectable after the user is authenticated, right?

[crazytonyli]

but these XMLRPC ones would only be detectable after the user is authenticated, right?

Yes, I plan to show them in error messages, which will be built on top of wordpress-mobile/WordPress-iOS#25183

[jkmassel]

Yes, I plan to show them in error messages

This is a separate type of error though – it's not a KnownAuthenticationBlockingPlugin. Can we introduce a different type and list for this to avoid making KnownAuthenticationBlockingPlugin more complex?

[crazytonyli]

Sure. I saw there is an xmlrpc function there, I thought I'd build on that.

But after a second look in the error message UI in the app, I think I'll stick with a general message for now.