Allow viewing MD files in GitLab

Problem/Motivation

Pasted from Slack:

I don't think there's anything the infra team can do here but double checking

We use MD files a lot with the AI initiative issues

Unfortunately, if you click on an attached MD file on an issue, it wants you to download it

It would be much better to allow viewing of the MD file

I'm assuming changing this won't be possible, right?

I guess we could rename to .md.txt?

Here's an example:

https://git.drupalcode.org/project/ai_context/-/work_items/3586147
https://git.drupalcode.org/-/project/191993/uploads/bdc9625673e049cdd31d...

Steps to reproduce

• Create a GitLab issue and attach an MD file
• Afterwards, it makes you download it rather than view it in the browser

Proposed resolution

drumm wrote in slack:

File an infrastructure issue, include a link to an issue with a MD file. We may be able to alter the response headers.

Remaining tasks

TBD

User interface changes

API changes

Data model changes