Add markdown support to exercise card and exercise preview

[bryanjenningz]

How to test:

• Go to /exercises/js0
• Check that markdown looks good

Before:

After:

[vercel]

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Name	Status	Preview	Comments	Updated
c0d3-app	✅ Ready (Inspect)	Visit Preview	✅ 2 resolved	Oct 3, 2022 at 3:25AM (UTC)

[codecov]

Codecov Report

Merging #2390 (53cf671) into master (e23446a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #2390   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          184       184           
  Lines         3281      3281           
  Branches       871       871           
=========================================
  Hits          3281      3281           

Impacted Files	Coverage Δ
components/ExerciseCard/ExerciseCard.tsx	100.00% <ø> (ø)
...onents/ExercisePreviewCard/ExercisePreviewCard.tsx	100.00% <ø> (ø)

[SlyBouhafs]

I approved it but there's a small issue though, you may want to check the comments on the vercel preview.

[bryanjenningz]

I approved it but there's a small issue though, you may want to check the comments on the vercel preview.

Thanks for finding that bug! I fixed it by adding "d-block" CSS classes to the Markdown components so all markdown is display: block.