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.go

@@ -19,7 +19,6 @@ import (
 	"encoding/pem"
 	"fmt"
 	"io"
-	"net/url"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -131,20 +130,6 @@ func (d DataSource) IsPostgres() bool {
 // A Topic in kafka.
 type Topic string
 
-// An Address to listen on.
-type Address string
-
-// An HTTPAddress to listen on, starting with either http:// or https://.
-type HTTPAddress string
-
-func (h HTTPAddress) Address() (Address, error) {
-	url, err := url.Parse(string(h))
-	if err != nil {
-		return "", err
-	}
-	return Address(url.Host), nil
-}
-
 // FileSizeBytes is a file size in bytes
 type FileSizeBytes int64