Suggestion: Missing `project.assets.json` as warning instead of an error

I was looking for an alternative to https://github.com/microsoft/sbom-tool with CycloneDX support and came across this repo. Thanks for the tool! :-)

One suggestion though: The SBOM generation failed for me because I had no project.assets.json in one of my subprojects. As a result no SBOM was generated at all. My preference would be to see missing project.assets.json as an warning that does not prevent the generation of the SBOM.

covenant/src/Covenant/Cli/Generate/GenerateCommand.cs

Line 67 in 0b5d762

return 1;

and

covenant/src/Covenant/Analysis/Dotnet/DotnetAnalyzer.cs

Line 214 in 0b5d762

    
           context.AddError($"Could not find [yellow]project.assets.json[/] at [yellow]{path}[/]");

What do you think?

@afrischk I think that an error is the best way to go here. However, there really should be a way of saying "I don't care about this project" and exclude the project from the SBOM.