Make server unix socket file permission configurable via flag UnixSocketPerm (#2763)

* feat(any): Add flag unixsocketperm with default 0017 - #2625

Signed-off-by: johannesengl <hello@johannesengl.com>

* feat(server): Update unix socket file perm based on config - #2625

Signed-off-by: johannesengl <hello@johannesengl.com>

* Fix default value of socket.

* Refactor unix socket file creation.

* Remove misplaced comment

---------

Signed-off-by: johannesengl <hello@johannesengl.com>
Co-authored-by: Caio Cotts <caio@cotts.com.br>
Co-authored-by: Deluan <deluan@navidrome.org>

conf/configuration.go

@@ -21,6 +21,7 @@ type configOptions struct {
 	ConfigFile                   string
 	Address                      string
 	Port                         int
+	UnixSocketPerm               string
 	MusicFolder                  string
 	DataFolder                   string
 	CacheFolder                  string
@@ -275,6 +276,7 @@ func init() {
 	viper.SetDefault("loglevel", "info")
 	viper.SetDefault("address", "0.0.0.0")
 	viper.SetDefault("port", 4533)
+	viper.SetDefault("unixsocketperm", "0660")
 	viper.SetDefault("sessiontimeout", consts.DefaultSessionTimeout)
 	viper.SetDefault("scaninterval", -1)
 	viper.SetDefault("scanschedule", "@every 1m")