[FR] Attack Navigator layer from ndjson export

**Is your feature request related to a problem? Please describe.**
This isn't a _problem_ but it would be a nice addition to the detection rules repo. The built-in navigator layers are helpful to visualize Elastic rule coverage, but as many people use their own rules, or duplicate rules from the repo, it doesn't accurately depict a customer's specific rule coverage.

**Describe the solution you'd like**
The ability to use a ndjson output of rules file and turn it into a Navigator layer.

**Additional context**
You're the best @brokensound77 ❤️