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_test.go

@@ -0,0 +1,25 @@
+package config
+
+import (
+	"io/fs"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHttpAddress_ParseGood(t *testing.T) {
+	address, err := HTTPAddress("http://localhost:123")
+	assert.NoError(t, err)
+	assert.Equal(t, "localhost:123", address.Address)
+	assert.Equal(t, "tcp", address.Network())
+}
+
+func TestHttpAddress_ParseBad(t *testing.T) {
+	_, err := HTTPAddress(":")
+	assert.Error(t, err)
+}
+
+func TestUnixSocketAddress_Network(t *testing.T) {
+	address := UnixSocketAddress("/tmp", fs.FileMode(0755))
+	assert.Equal(t, "unix", address.Network())
+}