feat(marketplace): cancel sell order

[technicallyty]

Description

• adds a CancelSellOrder msg to the marketplace

waiting on #870 to merge

Closes: #880

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[codecov]

Codecov Report

Merging #891 (4bacfdb) into master (70f0264) will increase coverage by 1.42%.
The diff coverage is 55.55%.

❗ Current head 4bacfdb differs from pull request most recent head e5bb564. Consider uploading reports for the commit e5bb564 to get more accurate results

@@            Coverage Diff             @@
##           master     #891      +/-   ##
==========================================
+ Coverage   72.42%   73.85%   +1.42%     
==========================================
  Files         194      174      -20     
  Lines       22900    22242     -658     
==========================================
- Hits        16585    16426     -159     
+ Misses       5073     4673     -400     
+ Partials     1242     1143      -99     

Flag	Coverage Δ
experimental-codecov	73.82% <55.55%> (+1.55%)	⬆️
stable-codecov	67.02% <55.55%> (+1.46%)	⬆️

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[ryanchristo]

Looks good to me.

[aleem1314]

lgtm