Fix emojis not showing in commit messages

[jamesa]

Fixes #5150

This fixes the issue where emojis were not showing up in the commit messages in the file tree, and on the commit view.

I was looking at two approaches for this:

1. Modify the code that generates the commit message links
2. Modify the frontend code that calls emojify

I went with the second approach and would like some feedback on that. I went this route instead of modifying the code that generates the commit link, since it looked like I would need to make a new processor in modules/markup/html.go to facilitate adding the has-emoji class to these links. And that seemed like overkill for this small use case.

It seems natural for emojify to work on children of the has-emoji elements, but it doesn't. (Deprecated, and only used to work by ID). So this will look at the children of each has-emoji element and insert emojis into any children that are links.

I only added emojis to links because I was worried about potential performance impacts if an element has a lot of children. If you think that's still a concern though then maybe we should go with the first approach?

Thanks for your consideration and feedback!

[jamesa]

Forgot to add screenshots:

[codecov-io]

Codecov Report

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The diff coverage is n/a.

@@           Coverage Diff            @@
##             master   #5168   +/-   ##
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  Coverage          ?   37.5%           
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  Files             ?     309           
  Lines             ?   45827           
  Branches          ?       0           
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  Hits              ?   17187           
  Misses            ?   26177           
  Partials          ?    2463

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