本地存储的缩略图144太小了，很难看清缩略图里的内容。

### Please make sure of the following things

- [x] I have read the [documentation](https://alist.nn.ci).
- [x] I'm sure there are no duplicate issues or discussions.
- [x] I'm sure this feature is not implemented.
- [x] I'm sure it's a reasonable and popular requirement.

### Description of the feature / 需求描述

看能不能提供选项，自定义缩略图的尺寸。或者保留原片尺寸？
现在代码里写死的144宽度的图片实在是有点小。毕竟是本地存储，对文件尺寸也不太敏感，建议适当大一点，720的宽度也ok的。
https://github.com/AlistGo/alist/blob/main/drivers/local/util.go#L140

### Suggested solution / 实现思路

_No response_

### Additional context / 附件

_No response_