feat: add build:test script and improve documentation code blocks

- Added a new script `build:test` to generate test cases from documentation code examples.
- Enhanced documentation files by ensuring proper code block formatting and adding missing closing backticks.
- Updated various markdown files to include new code blocks and fixed formatting issues.

packages/artplayer-vitepress/docs/en/component/contextmenu.md

@@ -124,4 +124,5 @@ art.on('ready', () => {
             html: 'Your New Menu',
         })
     }, 3000);
-});
+});
+```

packages/artplayer-vitepress/docs/en/component/controls.md

@@ -174,4 +174,5 @@ art.on('ready', () => {
             ],
         });
     }, 3000);
-});
+});
+```

packages/artplayer-vitepress/docs/en/component/layers.md

@@ -143,4 +143,5 @@ art.on('ready', () => {
             },
         });
     }, 3000);
-});
+});
+```

packages/artplayer-vitepress/docs/en/component/setting.md

@@ -168,6 +168,8 @@ var art = new Artplayer({
     ],
 });
 
+```
+
 ## Create - Toggle Button
 
 | Property   | Type                | Description               |
@@ -329,4 +331,5 @@ art.on('ready', () => {
             switch: false,
         });
     }, 3000);
-});
+});
+```