[MM-37074] Encapsulate inserted GIFs in inline image markdown

[Roy-Orbison]

Summary

Changes Markdown inserted by GIF picker from

https://thumbs.gfycat.com/LikableValidAlpineroadguidetigerbeetle-size_restricted.gif

to

![Beverly Hills Cop - OK gesture](https://thumbs.gfycat.com/LikableValidAlpineroadguidetigerbeetle-size_restricted.gif)

Ticket Link

As per Other notes of [MM-12290]
https://mattermost.atlassian.net/browse/MM-37074

Screenshots

Release Note

Improved default rendering of images inserted via the GIF picker.

[mattermod]

Hello @Roy-Orbison,

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[srkgupta]

Adding myself to check the CodeQL alert created on this PR

[Roy-Orbison]

Is this check somehow aware of Markdown syntax, thus expecting the .replace() to also escape possible \ in title properties? Or is it balking at the escaped [ in the regex? Or incorrectly parsing the escaped \ in the replacement string?

[srkgupta]

Is this check somehow aware of Markdown syntax, thus expecting the .replace() to also escape possible \ in title properties? Or is it balking at the escaped [ in the regex? Or incorrectly parsing the escaped \ in the replacement string?

@Roy-Orbison the alert did not consider the Markdown syntax and hence it's a false positive. The changes LGTM and I have dismissed the alert.

[hmhealey]

Thanks for the PR, @Roy-Orbison! Good catch on the followup to that ticket since it doesn't look like one was created to actually track this separately

[hmhealey]

Also good call escaping the square brackets in the gif title

[Roy-Orbison]

It doesn't escape \ characters a well, but that's because the flavour of markdown in MM simply looks for a \ preceding a square bracket. So [\\[x\]](#y) renders like this on GH [\x], but the first [\ of that rendering is included in the link text on MM.

Markdown is a little ill-defined.

[hmhealey]

We do plan on switching MM's Markdown to CommonMark which should match GitHub more closely, so we'll likely have to start doing that eventually, but I don't think it's a concern for now. The only way I see this becoming a concern is if Gfycat starts sending us bad data anyway.

[Roy-Orbison]

All user data is bad data ;)

[Roy-Orbison]

I tested on that build instance, and the gif markdown worked in all three contexts that receive the updated function parameter (create post, edit post, create comment).

[jgilliam17]

Thanks @Roy-Orbison
Tested, looks good to merge.

• Verified GIF inline markdown

[mm-cloud-bot]

Test server destroyed