Refactor the CLI markup code to make it re-useable

tools/utils/hostname.go

@@ -0,0 +1,24 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package utils
+
+import (
+	"fmt"
+	"os"
+)
+
+var _ = fmt.Print
+
+var hostname string = "*"
+
+func CachedHostname() string {
+	if hostname == "*" {
+		h, err := os.Hostname()
+		if err != nil {
+			hostname = h
+		} else {
+			hostname = ""
+		}
+	}
+	return hostname
+}