Code generation problem if project name contains "-" (dash, minus)

### Describe the bug
`dotnet new mvc` command produces faulty style reference if project name contains - character.

### To Reproduce
Using cli version 6.0.2.

```
mkdir cloud-manager
cd cloud-manager
dotnet new mvc
```

### Further technical details
The cli generated the project successfuly. But the _layout.cshtml file has a reference to "cloud_manager.styles.css" which needs to be "cloud-manager.styles.css". So until changing the _ to -, the site doesn't look properly due to a 404 error.

The generator seems falsely to use root namespace name instead of project output name.