Adding button to change layout

front/src/Components/Video/ChatLayout.svelte

@@ -0,0 +1,30 @@
+<script lang="ts">
+    import Peer from "./Peer.svelte";
+    import {layoutStore} from "../../Stores/LayoutStore";
+    import {onDestroy} from "svelte";
+
+    let cssClass = 'one-col';
+
+    const unsubscribe = layoutStore.subscribe((displayableMedias) => {
+        const nbUsers = displayableMedias.size;
+        if (nbUsers <= 1) {
+            cssClass = 'one-col';
+        } else if (nbUsers <= 4) {
+            cssClass = 'two-col';
+        } else if (nbUsers <= 9) {
+            cssClass = 'three-col';
+        } else {
+            cssClass = 'four-col';
+        }
+    });
+
+    onDestroy(() => {
+        unsubscribe();
+    });
+</script>
+
+<div class="chat-mode {cssClass}">
+    {#each [...$layoutStore.values()] as peer (peer.uniqueId)}
+        <Peer peer={peer}></Peer>
+    {/each}
+</div>