Refactor unit tests to TUnit framework

[jozefizso]

TUnit improves the performance a lot:

dotnet test

Test run summary: Passed!
  total: 39
  failed: 0
  succeeded: 36
  skipped: 3
  duration: 1s 895ms

Former xunit tests:

dotnet test

[xUnit.net 00:00:02.31]   Finished:    Kavod.Vba.Compression.Tests
  Kavod.Vba.Compression.Tests test net10.0 succeeded (3.0s)
[xUnit.net 00:00:02.43]   Finished:    Kavod.Vba.Compression.Tests
  Kavod.Vba.Compression.Tests test net8.0 succeeded (3.2s)

Test summary: total: 78, failed: 0, succeeded: 72, skipped: 6, duration: 3.2s
Build succeeded in 4.4s

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