Allow to stop a shared screen

Add a control button in a shared video which allow to stop only this shared video.

static/sfu.html

@@ -208,6 +208,9 @@
 
     <div id="videocontrols-template" class="invisible">
       <div class="video-controls vc-overlay">
+        <span class="stopsharing invisible" title="Stop Sharing">
+          <i class="fas fa-stop" data-type="bt-fullscreen" aria-hidden="true"></i>
+        </span>
         <span class="volume" title="Volume">
           <i class="fas fa-volume-up" data-type="bt-volume" aria-hidden="true"></i>
         </span>

static/sfu.js

@@ -1074,8 +1074,14 @@ function setMedia(c, isUp, video) {
                     volume.classList.add("fa-volume-off");
                 }
             }
-            if (local_media && local_media.kind === "local")
-                volume.parentElement.remove();
+            if(local_media)
+                if(local_media.kind === "local")
+                    volume.parentElement.remove();
+                else if (local_media.kind === "screenshare") {
+                    let stop = controls.querySelector(".stopsharing");
+                    stop.classList.remove('invisible');
+                    volume.parentElement.remove();
+                }
         }
 
         media.srcObject = c.stream;
@@ -1171,6 +1177,24 @@ function registerControlEvent(peerid) {
             }
         };
     }
+
+    let stop = /** @type {HTMLElement} */(peer.querySelector(".stopsharing"));
+    if (stop) {
+        stop.onclick = function(event) {
+            event.preventDefault();
+            let video = getParentVideo(event.target);
+            let video_id = video.id.split("-")[1];
+            for(let id in serverConnection.up) {
+                if (video_id === id) {
+                    let c = serverConnection.up[id];
+                    c.close(true);
+                    delMedia(id);
+                    delete(serverConnection.up[id]);
+                    setButtonsVisibility();
+                }
+            }
+        };
+    }
 }