Add option to cache remote image locally

[Lruihao]

Why

With the GetRemote function provided by hugo and some robust matching methods, FixIt now can cache remote images locally. This feature mainly focus on adding height and width to remote images in markdown to prevent layout shifts, caching these images locally is more like an added benefit. The advantages and disadvantages of this feature are relatively obvious, so it will be offered as an option(off by default) to the user.

Fixes #348

Pros

• Automatically add width and height to images on remote sources, avoid the occurrence of layout shift.
• Improve the consistency of the page loading experience.
• Lots of features can be achieved with the images cached locally, such as letting hugo crop different size images for responsive loading, or even better, convert these images to modern webp format while resizing.
• Does not support formats such as SVG and AVIF, and does not support request images (such as Gravetar)

Cons

• ✅ May cause CDN image to be unavailable.
• More local disk space required.
• Site build time will be affected by th loading speed of remote images.

Reference

• Option to cache remote image locally. HEIGE-PCloud/DoIt#860

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
fixit	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 26, 2023 8:52am

[Lruihao]

处理思路

1. 缓存图床图片到本地
2. 获取图片的宽高并设置
3. 可选择是否使用本地图片覆盖图床图片地址

配置

0.3.0 迁移到 params.page.cacheRemoteImages

目前的思路虽然解决了图床图片无法获取高度导致懒加载时锚点跳转错位的问题，但是又带来了不少弊端，所以该配置为试验性功能，需要的自行开启：

# FixIt 0.3.0 | NEW [Experimental] cache remote images locally, see: https://github.com/hugo-fixit/FixIt/pull/362
# FixIt 0.3.0 | 新增 [试验性功能] 缓存图床图片到本地，详见：https://github.com/hugo-fixit/FixIt/pull/362
[params.page.cacheRemoteImages]
  enable = false
  # replace remote image url with local image url
  # 用本地图片链接替换远程图片链接
  replace = false