[Bug][BuildCheck]: DirectorySeparator is incorrectly shown on unix

[f-alizada]

Issue Description

While reporting the SharedOutputPathAnalyzer shares the path like following:

 MSBUILD : warning : BC0101: Projects FooBar-Copy.csproj and FooBar.csproj have conflicting output paths: /home/user/project/bin\Debug/net8.0/.
  MSBUILD : warning : BC0101: Projects FooBar-Copy.csproj and FooBar.csproj have conflicting output paths: /home/user/project/obj/Debug/net8.0/.

Steps to Reproduce

Repro projects could be found here:

msbuild/src/BuildCheck.UnitTests/EndToEndTests.cs

Line 36 in d542f3a

public void SampleAnalyzerIntegrationTest(bool buildInOutOfProcessNode, bool analysisRequested)

run the msbuild with buildcheck enabled on unix.

Expected Behavior

The output path should contain only / (directory separator) /home/user/project/bin\Debug/net8.0/

Actual Behavior

The output path contains \ (directory separator) /home/user/project/bin/Debug/net8.0/