Blocks: Adding a simple video block

[youknowriad]

closes #2149

This PR adds a simple video block. No advanced options for now.

[jasmussen]

Nice!!!! Works on frontend and backend. Great first iteration, probably totally fine to ship!

Future improvements would be to bring the alignments and the responsive stuff to this one, just like we have them for video embeds. 👍 👍

[codecov]

Codecov Report

Merging #2309 into master will increase coverage by 0.01%.
The diff coverage is 30.76%.

@@            Coverage Diff             @@
##           master    #2309      +/-   ##
==========================================
+ Coverage   25.37%   25.39%   +0.01%     
==========================================
  Files         151      152       +1     
  Lines        4705     4718      +13     
  Branches      792      794       +2     
==========================================
+ Hits         1194     1198       +4     
- Misses       2969     2976       +7     
- Partials      542      544       +2

Impacted Files	Coverage Δ
blocks/library/video/index.js	30.76% <30.76%> (ø)

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