[SaaS] Domain based rate limiting Webadmin management

[chibenwa]

Webadmin endpoints for #1926

Why: allow reuse the rate limiting component for on prem

curl -XPUT http://ip:port/domains/{domain}/ratelimits
 -H "Content-Type: application/json"
 -d '{
    "mailsSentPerMinute": 10,
    "mailsSentPerHours": 100,
    "mailsSentPerDays": 1000,
    "mailsReceivedPerMinute": 20,
    "mailsReceivedPerHours": 200,
    "mailsReceivedPerDays": 2000
}'

And

curl -XGET http://ip:port/users/{username}/ratelimits

Returns the limits of a user:

{
    "mailsSentPerMinute": 10,
    "mailsSentPerHours": 100,
    "mailsSentPerDays": 1000,
    "mailsReceivedPerMinute": 20,
    "mailsReceivedPerHours": 200,
    "mailsReceivedPerDays": 2000
}

Definition of done

• Unit tests
• Guice bindings
• doc