Tests: remove dependency on CurrentDirectory ("test.ok" files)

[majocha]

This is mostly cherrypick from #17662.

A lot of FSharpSuite tests write a "test.ok" file to current dir to signal success. This is bad because current directory is a shared resource.

This makes them write to stdout instead.
Not pretty either, but Console.Out can be very simply intercepted in a multi-threaded way to unblock running those tests in parallel.

Inspired by #17709.

[github-actions]

✅ No release notes required

[majocha]

Tested contributor scenario on WIndows:
With env variable BUILDING_USING_DOTNET=true

git clean -xdf
dotnet build .\FSharp.Compiler.Service.sln
dotnet test .\tests\FSharp.Compiler.ComponentTests\

Tests running fine.

[majocha]

I also added BUILDING_USING_DOTNET condition to FSharpSuite.Tests.

Now

dotnet test .\tests\fsharp --filter "nameof-fsi"

Verifies the relevant test successfully runs RunFSharpScriptAndPrintOutput target.