Provide comment view under /comment/123

[Nutomic]

This address is linked when a Lemmy comment is shown in other software, eg Mastodon or Pleroma. At the moment, clicking on it will lead to a 404 page. We should provide a comment view under that address, or at least a redirect to the existing /post/123/comment/123 url.

See #1912 for details.

[dessalines]

We don't currently have a GetComment in the API, because I wanted that to be a little more advanced, IE show things like context, show child comments, etc. Like so:

Two options:

• Create a GetComment endpoint, that doesn't have any options, only shows the comment, and maybe the post.
• Wait for Serverside Tree/Thread Order Sorting and Pageing Proposal #949 , since it will make all those options possible / better. Its something we have to do anyway.

[Nutomic]

Serverside comment trees are probably still some time away, right? So a simple GetComment endpoint seems like a good solution for now.

[dessalines]

Yeah I could do that without too much difficulty.