## Issue
Closes 4936: Don't process markdown formatting as lbry:// url previews
## Approach
Preamble:
- We want to convert plain `https://lbry.tv/befreeonlbry` to an embed, but not `[blah](https://lbry.tv/befreeonlbry)`.
- At the markdown/remark level, both formats resolve to the same node type, having a `link` and a `text`, with the 'text' being auto-filled with the `href` if there is no label.
Fix by assuming the link is the non-labelled format if the `text` is the same as `href`.
This opens up one corner-case that we can't handle, which is when the user explicitly set the label using the href, e.g. `[https://lbry.tv/befreeonlbry](https://lbry.tv/befreeonlbry)`. This will still resolve to an embed. There's not enough data at the parsed level differentiate this case -- we would need to parse the content ourself before `remark`, which I think is not worth it.
## Aside/Reminder
If you see that the link doesn't resolve to an embed regardless of the format used, that's probably just due to `5636: Disable video previews in comments/posts made by channels below a certain channel staked level`
d91530b0c8