unix socket support (#2974)

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Signed-off-by: `Boris Rybalkin <ribalkin@gmail.com>`

I need this for Syncloud project (https://github.com/syncloud/platform)
where I run multiple apps behind an nginx on the same RPi like device so
unix socket is very convenient to not have port conflicts between apps.
Also someone opened this Issue:
https://github.com/matrix-org/dendrite/issues/2924

---------

Co-authored-by: kegsay <kegan@matrix.org>
Co-authored-by: Till <2353100+S7evinK@users.noreply.github.com>

setup/config/config_address.go

@@ -0,0 +1,45 @@
+package config
+
+import (
+	"io/fs"
+	"net/url"
+)
+
+const (
+	NetworkTCP  = "tcp"
+	NetworkUnix = "unix"
+)
+
+type ServerAddress struct {
+	Address              string
+	Scheme               string
+	UnixSocketPermission fs.FileMode
+}
+
+func (s ServerAddress) Enabled() bool {
+	return s.Address != ""
+}
+
+func (s ServerAddress) IsUnixSocket() bool {
+	return s.Scheme == NetworkUnix
+}
+
+func (s ServerAddress) Network() string {
+	if s.Scheme == NetworkUnix {
+		return NetworkUnix
+	} else {
+		return NetworkTCP
+	}
+}
+
+func UnixSocketAddress(path string, perm fs.FileMode) ServerAddress {
+	return ServerAddress{Address: path, Scheme: NetworkUnix, UnixSocketPermission: perm}
+}
+
+func HTTPAddress(urlAddress string) (ServerAddress, error) {
+	parsedUrl, err := url.Parse(urlAddress)
+	if err != nil {
+		return ServerAddress{}, err
+	}
+	return ServerAddress{parsedUrl.Host, parsedUrl.Scheme, 0}, nil
+}