feat: Add support for dynamic thumbnails in Artplayer

The code changes introduce a new `art.thumbnails` property that allows for dynamic setting of thumbnails in Artplayer. This feature enhances the user experience by providing a visual preview of the video content.

packages/artplayer/types/option.d.ts

@@ -9,6 +9,33 @@ import Artplayer = require('./artplayer');
 
 export type CustomType = 'flv' | 'm3u8' | 'hls' | 'ts' | 'mpd' | 'torrent' | (string & Record<never, never>);
 
+export type Thumbnails = {
+    /**
+     * The thumbnail image url
+     */
+    url: string;
+
+    /**
+     * The thumbnail item number
+     */
+    number?: number;
+
+    /**
+     * The thumbnail column size
+     */
+    column?: number;
+
+    /**
+     * The thumbnail width
+     */
+    width?: number;
+
+    /**
+     * The thumbnail height
+     */
+    height?: number;
+};
+
 export type Option = {
     /**
      * The player id
@@ -228,32 +255,7 @@ export type Option = {
     /**
      * Custom thumbnail
      */
-    thumbnails?: {
-        /**
-         * The thumbnail image url
-         */
-        url: string;
-
-        /**
-         * The thumbnail item number
-         */
-        number?: number;
-
-        /**
-         * The thumbnail column size
-         */
-        column?: number;
-
-        /**
-         * The thumbnail width
-         */
-        width?: number;
-
-        /**
-         * The thumbnail height
-         */
-        height?: number;
-    };
+    thumbnails?: Thumbnails;
 
     /**
      * Custom subtitle option

packages/artplayer/types/player.d.ts

@@ -1,5 +1,5 @@
 import { CssVar } from './cssVar';
-import { CustomType } from './option';
+import { CustomType, Thumbnails } from './option';
 import { quality } from './quality';
 
 export type AspectRatio = 'default' | '4:3' | '16:9' | (`${number}:${number}` & Record<never, never>);
@@ -63,6 +63,8 @@ export declare class Player {
     set subtitleOffset(time: number);
     set switch(url: string);
     set quality(quality: quality[]);
+    get thumbnails(): Thumbnails;
+    set thumbnails(thumbnails: Thumbnails);
     pause(): void;
     play(): Promise<void>;
     toggle(): void;