Add support for Sourcelink

[tonerdo]

You can now specify that Coverlet uses SourceLink URIs in place of document paths in coverage results.

MSBuild:

dotnet test /p:CollectCoverage=true /p:UseSourceLink=true

Global Tool:

coverlet test-assembly.dll --target "dotnet" --targetargs "test test-project --no-build" --use-source-link

cc @ViktorHofer

Fixes #257

[codecov]

Codecov Report

Merging #260 into master will decrease coverage by 2%.
The diff coverage is 35.08%.

@@            Coverage Diff             @@
##           master     #260      +/-   ##
==========================================
- Coverage   95.44%   93.43%   -2.01%     
==========================================
  Files          16       16              
  Lines        1757     1783      +26     
==========================================
- Hits         1677     1666      -11     
- Misses         80      117      +37

Impacted Files	Coverage Δ
...overlet.core/Instrumentation/InstrumenterResult.cs	100% <ø> (ø)	⬆️
src/coverlet.core/Reporters/CoberturaReporter.cs	98.23% <100%> (-0.33%)	⬇️
src/coverlet.core/Instrumentation/Instrumenter.cs	98.95% <100%> (+0.01%)	⬆️
src/coverlet.core/Coverage.cs	85.15% <26%> (-14.37%)	⬇️

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[ViktorHofer]

You know that question was coming. When can we consume that change?

[tonerdo]

@ViktorHofer most likely tomorrow. I need to add a few more things before making a new release

[tonerdo]

@ViktorHofer sorry it took much longer than expected, here's the new release with source link support https://www.nuget.org/packages/coverlet.console/1.4.0