[Media Library] Get preview mime type from thumbnail (to support video thumbnail)

[darron1217]

What does it do?

It changes the way that CardPreview component determine mime type of media preview.

Why is it needed?

I've created plugin that generates video thumbnail.

https://github.com/darron1217/strapi-plugin-video-thumbnail

It generates thumbnail as png type.

Media Library regard it as video, so it tries to play it as a video even though it is an image.

Current Behavior

After merge

SideEffects?

I couldn't find side effect of this PR.

Other file types also works fine after merge.

Related issue(s)/PR(s)

#8575
(maybe) #8750

[codecov]

Codecov Report

Merging #9184 (b67160c) into master (5d8f5fb) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #9184   +/-   ##
=======================================
  Coverage   34.64%   34.64%           
=======================================
  Files        1308     1308           
  Lines       14431    14431           
  Branches     1432     1432           
=======================================
  Hits         5000     5000           
  Misses       8517     8517           
  Partials      914      914           

Flag	Coverage Δ
front	26.04% <ø> (ø)
unit	54.87% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...i-plugin-upload/admin/src/components/List/index.js	0.00% <ø> (ø)

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[soupette]

LGTM.

Thanks a lot for your contribution

[HichamELBSI]

LGTM

[derrickmehaffy]

This pull request has been mentioned on Strapi Community Forum. There might be relevant details there:

https://forum.strapi.io/t/new-release-strapi-v3-4-6/2631/1