Decouple video grid from video tile components

This is an attempt to address the feedback in https://github.com/vector-im/element-call/pull/1099#discussion_r1226863404 that the video grid and video tile components have become too tightly coupled. After this change, the only requirements that the video grid makes of its child components are:

- They accept ref, style, and item props
- They attach the ref and styles to a react-spring animated element

Note: I removed the video grid Storybook file, because I'm not aware of anyone using Storybook for development of Element Call beyond Robert, and it would take some effort to fix to work with these changes.

src/video-grid/TileWrapper.tsx

@@ -0,0 +1,101 @@
+/*
+Copyright 2023 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React, { FC, memo, ReactNode, RefObject, useRef } from "react";
+import { EventTypes, Handler, useDrag } from "@use-gesture/react";
+import { SpringValue, to } from "@react-spring/web";
+
+import { TileDescriptor } from "./TileDescriptor";
+import { ChildrenProperties } from "./VideoGrid";
+
+interface Props {
+  id: string;
+  onDragRef: RefObject<
+    (
+      tileId: string,
+      state: Parameters<Handler<"drag", EventTypes["drag"]>>[0]
+    ) => void
+  >;
+  targetWidth: number;
+  targetHeight: number;
+  item: TileDescriptor;
+  opacity: SpringValue<number>;
+  scale: SpringValue<number>;
+  shadow: SpringValue<number>;
+  shadowSpread: SpringValue<number>;
+  zIndex: SpringValue<number>;
+  x: SpringValue<number>;
+  y: SpringValue<number>;
+  width: SpringValue<number>;
+  height: SpringValue<number>;
+  children: (props: ChildrenProperties) => ReactNode;
+}
+
+/**
+ * A wrapper around a tile in a video grid. This component exists to decouple
+ * child components from the grid.
+ */
+export const TileWrapper: FC<Props> = memo(
+  ({
+    id,
+    onDragRef,
+    targetWidth,
+    targetHeight,
+    item,
+    opacity,
+    scale,
+    shadow,
+    shadowSpread,
+    zIndex,
+    x,
+    y,
+    width,
+    height,
+    children,
+  }) => {
+    const ref = useRef<HTMLElement | null>(null);
+
+    useDrag((state) => onDragRef?.current!(id, state), {
+      target: ref,
+      filterTaps: true,
+      preventScroll: true,
+    });
+
+    return (
+      <>
+        {children({
+          ref,
+          style: {
+            opacity,
+            scale,
+            zIndex,
+            x,
+            y,
+            width,
+            height,
+            boxShadow: to(
+              [shadow, shadowSpread],
+              (s, ss) => `rgba(0, 0, 0, 0.5) 0px ${s}px ${2 * s}px ${ss}px`
+            ),
+          },
+          targetWidth,
+          targetHeight,
+          item,
+        })}
+      </>
+    );
+  }
+);