Update malware scan service

Change how ONE website is scanned; send only what changes. `status` switches its scanning on or off. `preset` (integer) moves it to another Malware Scanner global configuration (id from "List malware scan presets") and keeps its status - to assign many websites to one configuration at once, always switching them on, use "Assign websites to a malware scan configuration" instead. `filesystem` and `content.included` choose what is scanned: `content.included` requires `filesystem` to be sent in the same request, but `filesystem` alone is valid. Changing `filesystem` always resets the exclusions to the new mode's default; it also resets the scanned areas to the new mode's default, unless `content.included` is sent in the same request. `content.excluded` and the schedule are NOT edited here: exclusions stay a dashboard-only setting and the schedule cascades from the configuration. Switching `status` to `enabled` on a website not yet registered with the scanning provider answers **409**. Requires a full-access token (read-only tokens answer 403). An unknown `preset` id answers 422.