specify the project file name when running dotnet publish to avoid issues when the folder contains a solution file

[adamsitnik]

While building the performance culture in CoreFX I have noticed that most of the devs can now easily run the performance repo microbenchmarks on their machine, however very few run Linux vs Windows comparison.

@sebastienros has recently shown me how to run BenchmarkDotNet benchmarks using this amazing repository and infrastructure.

I think that it would be great if we could use it to quickly compare .NET Core performance on Linux vs Windows on the same hardware. Disclaimer: I don't want the entire CoreFX Team to start pushing a lot of jobs to the ASP.NET Perf infra, I just want to make it easy for the Team to measure the OS difference quickly when needed.

I have already introduced some changes to the performance repository to make it possible:

dotnet/performance#591
dotnet/performance#592
dotnet/performance#594

The last problem that remains active is addressed by this PR.

If we run dotnet publish in given folder without specifying the project name:

• if the folder does not contain a .sln file, but a .csproj only, dotnet publish publishes only the .csproj (99.9% of the cases, worked for everyone so far)
• if the folder contains a .sln file, dotnet publish tries to publish all projects in given solution, including test projects etc. This is the problem in the performance repo where we have a solution file and a project file in the same folder. dotnet publish tries to publish a self-contained version of xunit test project and it fails.

  "Command dotnet publish -c Release -o /tmp/BenchmarksServer/iprzluxi.olr/performance/src/benchmarks/micro/published /p:BenchmarksAspNetCoreVersion=3.0.0-preview7.19325.1 /p:MicrosoftAspNetCoreAllPackageVersion=3.0.0-preview7.19325.1 /p:MicrosoftAspNetCoreAppPackageVersion=3.0.0-preview7.19325.1 /p:BenchmarksNETStandardImplicitPackageVersion=3.0.0-preview7.19325.1 /p:BenchmarksNETCoreAppImplicitPackageVersion=3.0.0-preview7.19325.1 /p:BenchmarksRuntimeFrameworkVersion=3.0.0-preview7-27825-02 /p:BenchmarksTargetFramework=netcoreapp3.0 /p:MicrosoftNETCoreAppPackageVersion=3.0.0-preview7-27825-02 /p:NETCoreAppMaximumVersion=99.9 /p:MicrosoftNETCoreApp30PackageVersion=3.0.0-preview7-27825-02 /p:MicrosoftNETPlatformLibrary=Microsoft.NETCore.App --framework netcoreapp3.0 --self-contained -r linux-x64  returned exit code 1 
Microsoft (R) Build Engine version 16.3.0-preview-19321-02+a5a222491 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 498.44 ms for /tmp/BenchmarksServer/iprzluxi.olr/performance/src/tools/Reporting/Reporting/Reporting.csproj.
  Restore completed in 689.74 ms for /tmp/BenchmarksServer/iprzluxi.olr/performance/src/harness/BenchmarkDotNet.Extensions/BenchmarkDotNet.Extensions.csproj.
  Restore completed in 1.33 sec for /tmp/BenchmarksServer/iprzluxi.olr/performance/src/benchmarks/micro/MicroBenchmarks.csproj.
  Restore completed in 1.46 sec for /tmp/BenchmarksServer/iprzluxi.olr/performance/src/tests/harness/BenchmarkDotNet.Extensions.Tests/BenchmarkDotNet.Extensions.Tests.csproj.
  Reporting -> /tmp/BenchmarksServer/iprzluxi.olr/performance/artifacts/bin/Reporting/Debug/netcoreapp3.0/Reporting.dll
  BenchmarkDotNet.Extensions -> /tmp/BenchmarksServer/iprzluxi.olr/performance/artifacts/bin/BenchmarkDotNet.Extensions/Release/netcoreapp3.0/linux-x64/BenchmarkDotNet.Extensions.dll
  BenchmarkDotNet.Extensions -> /tmp/BenchmarksServer/iprzluxi.olr/performance/src/benchmarks/micro/published/
  BenchmarkDotNet.Extensions -> /tmp/BenchmarksServer/iprzluxi.olr/performance/artifacts/bin/BenchmarkDotNet.Extensions/Release/netcoreapp3.0/BenchmarkDotNet.Extensions.dll
  MicroBenchmarks -> /tmp/BenchmarksServer/iprzluxi.olr/performance/artifacts/bin/MicroBenchmarks/Release/netcoreapp3.0/linux-x64/MicroBenchmarks.dll
  MicroBenchmarks -> /tmp/BenchmarksServer/iprzluxi.olr/performance/src/benchmarks/micro/published/
/tmp/BenchmarksServer/qt1c15ni.vyi/sdk/3.0.100-preview7-012605/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.RuntimeIdentifierInference.targets(131,5): error NETSDK1067: Self-contained applications are required to use the application host. Either set SelfContained to false or set UseAppHost to true. [/tmp/BenchmarksServer/iprzluxi.olr/performance/src/tests/harness/BenchmarkDotNet.Extensions.Tests/BenchmarkDotNet.Extensions.Tests.csproj]

The solution is to provide the project name when doing dotnet publish $projectName.

This should not be an issue, because this particular command expects user to provide the path via --project-file when running BenchmarkDriver. It's already used to get the WorkingDirectory for dotnet publish

Benchmarks/src/BenchmarksServer/Startup.cs

Lines 1423 to 1424 in 0969d63

	// Computes the location of the benchmarked app
	var benchmarkedApp = Path.Combine(path, benchmarkedDir, Path.GetDirectoryName(FormatPathSeparators(job.Source.Project)));

Benchmarks/src/BenchmarksServer/Startup.cs

Lines 1792 to 1793 in 0969d63

	var buildResults = ProcessUtil.Run(dotnetExecutable, arguments,
	workingDirectory: benchmarkedApp,