feat: Add Share option for artists, albums, and tracks

This feature is only available on the Subsonic media provider. Using a
Jellyfin server will make Supersonic hide the "Share" option.

* Artists: Option available in grid view and in Artist view.
* Albums: Option available in grid view and in Album view.
* Tracks: Option available in tracklist, when a single track is selected.

backend/mediaprovider/subsonic/subsonicmediaprovider.go

@@ -5,6 +5,7 @@ import (
 	"image"
 	"io"
 	"math"
+	"net/url"
 	"strconv"
 	"strings"
 	"sync"
@@ -315,6 +316,20 @@ func (s *subsonicMediaProvider) SetRating(params mediaprovider.RatingFavoritePar
 	return err
 }
 
+func (s *subsonicMediaProvider) CreateShareURL(id string) (*url.URL, error) {
+	share, err := s.client.CreateShare(id, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	shareUrl, err := url.Parse(share.Url)
+	if err != nil {
+		return nil, err
+	}
+
+	return shareUrl, nil
+}
+
 func (s *subsonicMediaProvider) DownloadTrack(trackID string) (io.Reader, error) {
 	return s.client.Download(trackID)
 }