Add GoSRT & improvements (repo-merge)

Commits (Ingo Oppermann):
- Add experimental SRT connection stats and logs
- Hide /config/reload endpoint in reade-only mode
- Add SRT server
- Create v16 in go.mod
- Fix data races, tests, lint, and update dependencies
- Add trailing slash for routed directories (datarhei/restreamer#340)
- Allow relative URLs in content in static routes

Co-Authored-By: Ingo Oppermann <57445+ioppermann@users.noreply.github.com>

vendor/github.com/datarhei/gosrt/doc.go

@@ -0,0 +1,61 @@
+/*
+Package srt provides an interface for network I/O using the SRT protocol (https://github.com/Haivision/srt).
+
+The package gives access to the basic interface provided by the Dial, Listen, and Accept functions and the associated
+Conn and Listener interfaces.
+
+The Dial function connects to a server:
+
+	conn, err := srt.Dial("srt", "golang.org:6000", srt.Config{
+		StreamId: "...",
+	})
+	if err != nil {
+		// handle error
+	}
+
+	buffer := make([]byte, 2048)
+
+	for {
+		n, err := conn.Read(buffer)
+		if err != nil {
+			// handle error
+		}
+
+		// handle received data
+	}
+
+	conn.Close()
+
+The Listen function creates servers:
+
+	ln, err := srt.Listen("srt", ":6000", srt.Config{...})
+	if err != nil {
+		// handle error
+	}
+
+	for {
+		conn, mode, err := ln.Accept(handleConnect)
+		if err != nil {
+			// handle error
+		}
+
+		if mode == srt.REJECT {
+			// rejected connection, ignore
+			continue
+		}
+
+		if mode == srt.PUBLISH {
+			go handlePublish(conn)
+		} else {
+			go handleSubscribe(conn)
+		}
+	}
+
+The ln.Accept function expects a function that takes a srt.ConnRequest
+and returns a srt.ConnType. The srt.ConnRequest lets you retrieve the
+streamid with on which you can decide what mode (srt.ConnType) to return.
+
+Check out the Server type that wraps the Listen and Accept into a
+convenient framework for your own SRT server.
+*/
+package srt