Show DisplayName for conflicting actions

[Saibamen]

Just like in Swashbuckle (https://github.com/domaindrivendev/Swashbuckle.AspNetCore/blob/master/src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/SwaggerGenerator.cs#L290).

Reduce some code differences between AspNetCore and NSwag.Generation.WebApi projects.

Before

After

[Saibamen]

And for ASP.NET Framework:

[lahma]

Are you sure the PR scope is still according to the title?

[Saibamen]

Yes. I added NSwag.Sample.AspNet project, because in this repository we have only .NET >= 8 sample projects

[Saibamen]

OK, forget about NSwag.Sample.AspNet... I don't have time to fight with build errors about "missing nuget package" for old .NET Framework build solutions in GitHub Actions generated with Nuke.

[Saibamen]

Rerun GH Actions to "fix" flaky tests in master branch...

GitHub Actions / ubuntu-latest
NSwag.ConsoleCore.Tests.GenerateSampleSpecificationTests.Should_generate_openapi_for_project(projectName: "NSwag.Sample.NET90Minimal"

System.InvalidOperationException : Process must exit before requested information can be determined.