feat(blocksync): `share.WriteEDS`

[distractedm1nd]

Closes #1105

Still a few todos to be solved and comments to be added, but its ready for the first round of reviews now

Will change the base branch of the PR to the feature branch when it is set up (I will wait until there is preliminary work on it)

[codecov-commenter]

Codecov Report

Merging #1139 (79c5409) into main (d239616) will increase coverage by 0.05%. The diff coverage is 61.80%.

@@            Coverage Diff             @@
##             main    #1139      +/-   ##
==========================================
+ Coverage   55.86%   55.92%   +0.05%     
==========================================
  Files         160      161       +1     
  Lines        9725     9869     +144     
==========================================
+ Hits         5433     5519      +86     
- Misses       3756     3796      +40     
- Partials      536      554      +18     

Impacted Files	Coverage Δ
share/ipld/nmt_adder.go	74.50% <58.33%> (-4.98%)	:arrow_down:
share/eds/eds.go	62.12% <62.12%> (ø)
fraud/bad_encoding.go	63.00% <0.00%> (-3.00%)	:arrow_down:

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[Wondertan]

Let's also move this into share/eds