Skip connections bind to local IPAddress - #389

Context:
Client http request bind to local ip (ex 10.0.0.4) when communicating to the host endpoints, for example:

• uses ServicePoint.BindIPEndPointDelegate or
• uses curl --interface 10.0.0.4 curl(1) - Linux manual page.

GPA ProxyServer listens to loopback/localhost IP, but OS networking kernel, not eBPF, could NOT redirect such requests to loopback/localhost IP address. The OS rejects this because:

• Loopback is a closed loop: Traffic on 127.0.0.0/8 is expected to originate and terminate on the loopback interface. A packet with source 10.0.0.4 arriving on loopback violates this assumption.
• Reverse path validation: The kernel (Linux rp_filter, Windows strong host model) checks that the source IP is reachable via the interface the packet arrives on. 10.0.0.4 is not reachable via loopback, so the packet is dropped.
• Route selection: The kernel picks the outgoing interface based on the destination. For 127.0.0.1, it selects loopback. But the bound source IP doesn't belong to loopback, causing a "network unreachable" or silent drop.

Changes:

• Add ebpf map config_map to accept settings GPA_CONFIG_LOCAL_IP_BIND_MONITOR_ONLY
• Add ebpf map audit_only_map to cache connections bind to local IP address
• if GPA_CONFIG_LOCAL_IP_BIND_MONITOR_ONLY set, skip the redirect if the connections bind to local IP Address
• Start poll_audit_only task to read/pop the elem from ebpf map audit_only_map and emit telemetry event every few seconds.

Known issue:

• As the poll_audit_only task to read/pop every few seconds, the process details may not available if the process exits quickly