feat: new Live Collaboration Component API (#6104)

* feat: new Live Collaboration Component API

* namespace export icons into `icons` dictionary and lowercase

* update readme and changelog

* review fixes

* fix

* fix

* update docs

* remove

* allow button rest props

* update docs

* docs

* add `WelcomeScreen.Center.MenuItemLiveCollaborationTrigger`

* fix lint

* update changelog

Co-authored-by: dwelle <luzar.david@gmail.com>

src/components/live-collaboration/LiveCollaborationTrigger.tsx

@@ -0,0 +1,40 @@
+import { t } from "../../i18n";
+import { usersIcon } from "../icons";
+import { Button } from "../Button";
+
+import clsx from "clsx";
+import { useExcalidrawAppState } from "../App";
+
+import "./LiveCollaborationTrigger.scss";
+
+const LiveCollaborationTrigger = ({
+  isCollaborating,
+  onSelect,
+  ...rest
+}: {
+  isCollaborating: boolean;
+  onSelect: () => void;
+} & React.ButtonHTMLAttributes<HTMLButtonElement>) => {
+  const appState = useExcalidrawAppState();
+
+  return (
+    <Button
+      {...rest}
+      className={clsx("collab-button", { active: isCollaborating })}
+      type="button"
+      onSelect={onSelect}
+      style={{ position: "relative" }}
+      title={t("labels.liveCollaboration")}
+    >
+      {usersIcon}
+      {appState.collaborators.size > 0 && (
+        <div className="CollabButton-collaborators">
+          {appState.collaborators.size}
+        </div>
+      )}
+    </Button>
+  );
+};
+
+export default LiveCollaborationTrigger;
+LiveCollaborationTrigger.displayName = "LiveCollaborationTrigger";