When true, read the client IP from the proxy header instead of
request.ip. Requires a trusted reverse proxy. Default: false.
WARNING: on its own this trusts the header's LEFTMOST entry, which is safe
only behind a proxy that OVERWRITES the header. The standard nginx idiom
appends instead, in which case the leftmost entry is whatever the client
sent — set IpSecurityOptions.trustedProxies or
IpSecurityOptions.proxyHops so the client is resolved from the
right. Note that with false, clientIp is undefined on all
first-party adapters (see the module note).