Move to coverlet.collector

[Evangelink]

CI builds are sometime failing with the following error:

D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error : Unable to read beyond the end of the stream. [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error :    at System.IO.BinaryReader.FillBuffer(Int32 numBytes) [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error :    at System.IO.BinaryReader.ReadInt32() [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error :    at Coverlet.Core.Coverage.CalculateCoverage() in /_/src/coverlet.core/Coverage.cs:line 414 [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error :    at Coverlet.Core.Coverage.GetCoverageResult() in /_/src/coverlet.core/Coverage.cs:line 161 [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
D:\a\_work\1\s\.packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error :    at Coverlet.MSbuild.Tasks.CoverageResultTask.Execute() in /_/src/coverlet.msbuild.tasks/CoverageResultTask.cs:line 83 [D:\a\_work\1\s\src\Roslyn.Diagnostics.Analyzers\UnitTests\Roslyn.Diagnostics.Analyzers.UnitTests.csproj]
##[error].packages\coverlet.msbuild\3.1.2\build\coverlet.msbuild.targets(71,5): error : (NETCORE_ENGINEERING_TELEMETRY=Build) Unable to read beyond the end of the stream.
   at System.IO.BinaryReader.FillBuffer(Int32 numBytes)
   at System.IO.BinaryReader.ReadInt32()
   at Coverlet.Core.Coverage.CalculateCoverage() in /_/src/coverlet.core/Coverage.cs:line 414
   at Coverlet.Core.Coverage.GetCoverageResult() in /_/src/coverlet.core/Coverage.cs:line 161
   at Coverlet.MSbuild.Tasks.CoverageResultTask.Execute() in /_/src/coverlet.msbuild.tasks/CoverageResultTask.cs:line 83

This is a known issue of coverlet (vstest to be exact) listed here: https://github.com/coverlet-coverage/coverlet/blob/master/Documentation/KnownIssues.md#vstest-stops-process-execution-early

Potential workaround is to use the environment variable that increase the timeout time (see microsoft/vstest#3466) by setting VSTEST_TESTHOST_SHUTDOWN_TIMEOUT.