oEmbed support

[JuniorJPDJ]

it's neccessary for mastodon and lots of other things

mastodon/mastodon#18701

[yurbash]

Since the Piped team is busy fighting with YouTube's roadblocks, this repo does not get a lot of attention. So I have started working on my own opengraph proxy.

You can can check my oEmbed progress here: yurbash/piped-html-proxy-go#2