Add alternate link source dropdown

[jwr1]

Describe the feature

As described in this post, we have to steal another Lemmy app's feature. This will provide alternative sources (in a menu) when a Link-only post is viewed (not an image or discussion). This would be useful if the linked article is paywalled or otherwise inaccessible.

Recommended sources are (from here):

Archive Today: https://archive.ph/%s
Ghost Archive: https://ghostarchive.org/search?term=%s
12ft.io: https://12ft.io/proxy?q=%s
Ground News (not an archive provider, but can search for similar stories that may not be paywalled): https://ground.news/find?url=%s

For YouTube videos, we could also provide alternate links to piped or invidious.

Additional context

No response

[jwr1]

Complete in e1bfacb9f54e94dd35e4f5156c7ba54767e02d0a.