test(share): add Full Node reconstruction tests

[Wondertan]

Mainly:

• Improves testnet utility in share pkg
• Introduces tests that assert that our reconstruction works in semi-ideal scenarios with values taken from the original paper
  • 1x One Full and multiple Lights
  • 2x Two Fulls and two subnets with multiple Lights that cannot reconstruct data on their own

For an in-depth description of each test consult a complementary comment to each test.

Substitutes #598
Based on #682
Closes #600

My favourite part about these tests is that they won't require any changes if we e.g., move to a completely new protocol for Share transportation

[adlerjohn]

Did you link to the right issue? #598 is a closed PR.

[adlerjohn]

Is this going to be merged into #682, or does it require #682 to be merged into main first? If the latter, please convert this into a draft to avoid merging too soon.

[Wondertan]

Draft until #682 is merged

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.00000% with 21 lines in your changes missing coverage. Please review.

Project coverage is 54.19%. Comparing base (0f8b81c) to head (16143c5).
Report is 1488 commits behind head on main.

Files with missing lines	Patch %	Lines
service/share/testing.go	75.00%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #702      +/-   ##
==========================================
+ Coverage   53.93%   54.19%   +0.25%     
==========================================
  Files         121      121              
  Lines        6968     7016      +48     
==========================================
+ Hits         3758     3802      +44     
- Misses       2823     2830       +7     
+ Partials      387      384       -3     

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[Wondertan]

So the main blocker here is to make tests run while being limited with 8k goroutines, which is not trivial.

[Wondertan]

No plan yet. I would like to have them merged so hard, so I will probably disable the race flag for them somehow

[Wondertan]

Also, it would be good to extend these tests with discovery

[Wondertan]

I extracted the tests and disabled the race detector for them. Fully ready for review

[Wondertan]

@musalbas, added you here as a reviewer. Do we need more harness tests or is this enough? Do we need tests where there are more than two Fulls with their own subnetworks?

[musalbas]

In general we need to test multiple full nodes, but I'm not sure if that's something we need as a harness test, but rather a network test using e.g. testground.

[Wondertan]

Ok, then I think there is nothing else to do in this PR. Testground reconstruction test is planned but orthogonal to this PR.