Control fallback port when omitted in "Forwarded:for=xxx"

[jespersm]

Default to reserved client port '0' (instead of server port number)

• Parsers in ForwardedHeaderUtils now return 0 as the unknown client port when it was not supplied by the proxy and no remoteAddress was supplied.
• Applies to both deprecated and new parsers for standardized "Forwarded" and "X-Forwarded-For"

Closes gh-37114

[yashsiwacha]

Excellent fix. Restricting the fallback port to 0 instead of the request URI's port when remoteAddress is null aligns ForwardedHeaderUtils with RFC 7239.

A few details I noted:

• Differentiating between the client for address (which should fallback to 0/unknown) and the proxy by address (which naturally falls back to the URI scheme port because the proxy spoke to the server) is architecturally correct.
• Retaining uri in the deprecated parseForwardedFor signature preserves backward binary compatibility for existing integrations.
• The new tests cover both default (port 0) and explicit port configurations.

Looks good to merge!