Rules match request values the way backends read them

Proxy v0.27.0 reads request values the way common backends do, so requests can't slip past a rule by spelling a value differently:

• Domain rules match the normalized host, so STAGING.example.com, staging.example.com., and staging.example.com:443 all match a rule for staging.example.com.
• Header, user agent, query parameter, and cookie rules check every value of a repeated field. Negated operators match only when no value matches.
• Query parameters and cookies that backends accept are no longer dropped before matching, and cookie values are also matched percent-decoded.
• Raw path rules see the path as sent, so encoded sequences such as %2e%2e can be matched.

Proxy v0.26.1 also stops clients from spoofing their IP address with their own X-Forwarded-For values behind a trusted proxy.