Fix issue with popover on full sn links

[tsmith123]

Fixes #1213

Description

This PR ensures a popover is seen for internal links that include a text part.

Tests

These links were tested and are working as expected:

Link	Comment
http://localhost:3000/items/459356	shows popover and renders internal link
[link](http://localhost:3000/items/458213	shows popover and renders internal link
[link](https://stacker.news)	opens in new tab (this is external relative to localhost)
https://stacker.news	opens in new tab (this is external relative to localhost)
[link](http://localhost:3000/settings)	renders internal link (no popover)
[link](/settings)	renders internal link (no popover)

Screenshots

Preview

Popover visible on second link

[huumn]

We didn't want to change the behavior of [something](/items/423) to display as #423 in this one. Otherwise, this is good. Note to self, that function is getting pretty gnarly.

[tsmith123]

Ah, didn't consider that scenario. Yeah the function is getting messy and difficult to make changes without breaking something. Really need unit tests so when someone with little experience of the codebase makes changes they can be sure they haven't broken something.

I can start adding some unit tests around the codebase if that's any help?

[huumn]

@ekzyis and I have been discussing tests more, trying to figure out where they're good, where they're bad. We should have a public discussion at some point about it, but until then let's hold off.