Added Navigation service (#5)

InfiniTime implements a [Navigation Service](https://github.com/InfiniTimeOrg/InfiniTime/blob/develop/doc/NavigationService.md). This pull request will add it to the go library by defining a function
```go
func (i *Device) Navigation(flag string, narrative string, dist string, progress uint8) error {
  ...
}
```
From the InfiniTime manual
 * `flag`: the graphic instruction as provided by [Pure Maps](https://github.com/rinigus/pure-maps/tree/master/qml/icons/navigation). A list of valid instruction icons can be found [here](https://github.com/rinigus/pure-maps/tree/master/qml/icons/navigation)
 * `narrative`: the instruction in words, eg. "At the roundabout take the first exit".
 * `dist`: a short string describing the distance to the upcoming instruction such as "50 m".
 * `progress`: the percent complete in a `uint8`

Adding this to the `itd` daemon is straightforward
```patch
diff --git a/api/types.go b/api/types.go
index 281a85b..14c84de 100644
--- a/api/types.go
+++ b/api/types.go
@@ -22,6 +22,13 @@ type FwUpgradeData struct {
        Files []string
 }

+type NavigationData struct {
+       Flag         string
+       Narrative    string
+       Dist         string
+       Progress     uint8
+}
+
 type NotifyData struct {
        Title string
        Body  string
diff --git a/socket.go b/socket.go
index 6fcba5c..91b37c0 100644
--- a/socket.go
+++ b/socket.go
@@ -204,6 +204,10 @@ func (i *ITD) Address(_ *server.Context) string {
        return i.dev.Address()
 }

+func (i *ITD) Navigation(_ *server.Context, data api.NavigationData) error {
+       return i.dev.Navigation(data.Flag, data.Narrative, data.Dist, data.Progress)
+}
+
 func (i *ITD) Notify(_ *server.Context, data api.NotifyData) error {
        return i.dev.Notify(data.Title, data.Body)
 }
```

Co-authored-by: Yannick Ulrich <yannick.ulrich@durham.ac.uk>
Reviewed-on: https://gitea.arsenm.dev/Arsen6331/infinitime/pulls/5
Co-authored-by: yannickulrich <yannick.ulrich@protonmail.com>
Co-committed-by: yannickulrich <yannick.ulrich@protonmail.com>

infinitime.go

@@ -52,6 +52,10 @@ var charNames = map[string]string{
 	FSTransferChar:  "Filesystem Transfer",
 	FSVersionChar:   "Filesystem Version",
 	WeatherDataChar: "Weather Data",
+	NavFlagsChar:    "Navigation Icon",
+	NavNarrativeChar:"Navigation Instruction",
+	NavManDistChar:  "Navigation Distance to next event",
+	NavProgressChar: "Navigation Progress",
 }
 
 type Device struct {
@@ -67,10 +71,13 @@ type Device struct {
 	fsVersionChar   *gatt.GattCharacteristic1
 	fsTransferChar  *gatt.GattCharacteristic1
 	weatherDataChar *gatt.GattCharacteristic1
+	weatherdataChar *gatt.GattCharacteristic1
 	notifEventCh    chan uint8
 	notifEventDone  bool
 	Music           MusicCtrl
+	Navigation      NavigationCtrl
 	DFU             DFU
+	navigationEv    NavigationEvent
 }
 
 var (
@@ -394,6 +401,14 @@ func (i *Device) resolveChars() error {
 		charResolved := true
 		// Set correct characteristics
 		switch char.Properties.UUID {
+		case NavFlagsChar:
+			i.Navigation.flagsChar = char
+		case NavNarrativeChar:
+			i.Navigation.narrativeChar = char
+		case NavManDistChar:
+			i.Navigation.mandistChar = char
+		case NavProgressChar:
+			i.Navigation.progressChar = char
 		case NewAlertChar:
 			i.newAlertChar = char
 		case NotifEventChar:
@@ -723,6 +738,7 @@ func (i *Device) Notify(title, body string) error {
 	)
 }
 
+
 // These constants represent the possible call statuses selected by the user
 const (
 	CallStatusDeclined uint8 = iota