CookieStorage has been refactored to use HashMap with base domain as the
key. Values of hashmap is vector of cookies.
CookieStorage now has max_per_host which restricts maximum cookies that
can be added per base domain.
Cookie eviction doesnot take place if max_per_host is not reached.
Cookie eviction logic implemented here does following steps
1) Evict all expired cookies
2) Remove oldest accessed non-secure cookie If any
3) When no non-secure cookie exist, remove oldest accessed secure cookie
if new cookie being added is secure. Else ignore new cookie
In rust-url 1.0 the `Url` struct is going to have private fields, and there
is no way to to create an aribitrary one without going through the parser.
The plugin never had a clear demonstrated performance benefit,
it was made mostly because it was possible and relatively easy at the time.
