core: Implement socket activation listeners (#6573)

* caddy adapt for listen_protocols

* adapt listen_socket

* allow multiple listen sockets for port ranges and readd socket fd listen logic

* readd logic to start servers according to listener protocols

* gofmt

* adapt caddytest

* gosec

* fmt and rename listen to listenWithSocket

* fmt and rename listen to listenWithSocket

* more consistent error msg

* non unix listenReusableWithSocketFile

* remove unused func

* doc comment typo

* nonosec

* commit

* doc comments

* more doc comments

* comment was misleading, cardinality did not change

* addressesWithProtocols

* update test

* fd/ and fdgram/

* rm addr

* actually write...

* i guess we doin' "skip": now

* wrong var in placeholder

* wrong var in placeholder II

* update param name in comment

* dont save nil file pointers

* windows

* key -> parsedKey

* osx

* multiple default_bind with protocols

* check for h1 and h2 listener netw

admin.go

@@ -313,7 +313,7 @@ func (admin AdminConfig) allowedOrigins(addr NetworkAddress) []*url.URL {
 	}
 	if admin.Origins == nil {
 		if addr.isLoopback() {
-			if addr.IsUnixNetwork() {
+			if addr.IsUnixNetwork() || addr.IsFdNetwork() {
 				// RFC 2616, Section 14.26:
 				// "A client MUST include a Host header field in all HTTP/1.1 request
 				// messages. If the requested URI does not include an Internet host
@@ -351,7 +351,7 @@ func (admin AdminConfig) allowedOrigins(addr NetworkAddress) []*url.URL {
 				uniqueOrigins[net.JoinHostPort("127.0.0.1", addr.port())] = struct{}{}
 			}
 		}
-		if !addr.IsUnixNetwork() {
+		if !addr.IsUnixNetwork() && !addr.IsFdNetwork() {
 			uniqueOrigins[addr.JoinHostPort(0)] = struct{}{}
 		}
 	}