Recursively refresh playlist tracks within smart playlist rules (#3018)

* Recursively refresh playlists within smart playlist rules

Signed-off-by: reillymc <reilly@mackenzie-cree.net>

* Clean up recursive smart playlist functions

Signed-off-by: reillymc <reilly@mackenzie-cree.net>

* Add smart playlist refresh timeout config and tests for nested track refetching

Signed-off-by: reillymc <reilly@mackenzie-cree.net>

* Change SmartPlaylistRefreshTimeout to SmartPlaylistRefreshDelay, increase default value

* Revert `smartPlaylistRefreshDelay` default to 5 seconds

---------

Signed-off-by: reillymc <reilly@mackenzie-cree.net>
Co-authored-by: Deluan <deluan@navidrome.org>

conf/configuration.go

@@ -49,6 +49,7 @@ type configOptions struct {
 	AutoImportPlaylists             bool
 	DefaultPlaylistPublicVisibility bool
 	PlaylistsPath                   string
+	SmartPlaylistRefreshDelay       time.Duration
 	AutoTranscodeDownload           bool
 	DefaultDownsamplingFormat       string
 	SearchFullString                bool
@@ -302,6 +303,7 @@ func init() {
 	viper.SetDefault("autoimportplaylists", true)
 	viper.SetDefault("defaultplaylistpublicvisibility", false)
 	viper.SetDefault("playlistspath", consts.DefaultPlaylistsPath)
+	viper.SetDefault("smartPlaylistRefreshDelay", 5*time.Second)
 	viper.SetDefault("enabledownloads", true)
 	viper.SetDefault("enableexternalservices", true)
 	viper.SetDefault("enablemediafilecoverart", true)