Run test by file path and line number

As a Ruby developer, I like to run tests like this :

```
rspec --color spec/services/orders/mark_error_service_spec.rb:19
```

As you can see, I specify the filepath and the line number. It's very useful for integration with text editors like vim. I know it's possible to filter by name but it's not very convenient.

Is it possible to run a test by specifying the file path and the like number?

No source file, test, or entry point is named. Start by reproducing the requested file-and-line invocation from the issue and tracing Karma's existing command-line test filtering; done means a documented and tested way to select the test at a given path and line.

Written by the indexing model from the issue text.