feat(gui, config): support simple folder grouping (fixes #2070) (#10563)

Adds a very simple way to group up folders to help with organising from
the GUI. 

Signed-off-by: Ben Norcombe <bennorcombe@pm.me>

lib/config/deviceconfiguration.go

@@ -36,6 +36,7 @@ type DeviceConfiguration struct {
 	Untrusted                bool              `json:"untrusted" xml:"untrusted"`
 	RemoteGUIPort            int               `json:"remoteGUIPort" xml:"remoteGUIPort"`
 	RawNumConnections        int               `json:"numConnections" xml:"numConnections"`
+	Group                    string            `json:"group" xml:"group,attr,omitempty"`
 }
 
 func (cfg DeviceConfiguration) Copy() DeviceConfiguration {

lib/config/folderconfiguration.go

@@ -54,6 +54,7 @@ type FolderConfiguration struct {
 	Path                    string                      `json:"path" xml:"path,attr"`
 	Type                    FolderType                  `json:"type" xml:"type,attr"`
 	Devices                 []FolderDeviceConfiguration `json:"devices" xml:"device"`
+	Group                   string                      `json:"group" xml:"group,attr,omitempty" restart:"false"`
 	RescanIntervalS         int                         `json:"rescanIntervalS" xml:"rescanIntervalS,attr" default:"3600"`
 	FSWatcherEnabled        bool                        `json:"fsWatcherEnabled" xml:"fsWatcherEnabled,attr" default:"true"`
 	FSWatcherDelayS         float64                     `json:"fsWatcherDelayS" xml:"fsWatcherDelayS,attr" default:"10"`