feat: creating templates from yaml config files

[ken-iks]

First shot at programmatic template creation. Functional for timeseries, geomap, histogram, and scatter panels. Added a USAGE.md to summarize current usage pattern.

[najork]

I'm philosophically OK with this going into experimental as a short-term solution, but we should start exploring first-class infrastructure as code solutions for declarative state management, e.g. https://developer.hashicorp.com/terraform

Defining Nominal resources in a source of truth outside of Nominal itself will be a common workflow. Users will want to define things like templates, checklists, etc externally and have a mechanism for syncing them with Nominal, with support for other nice things like GitOps workflows, etc.

Leveraging existing tooling to the extent possible reduces the product surface area that we need to own and maintain.

Eventually (and this is looking far out on the horizon) we can programmatically generate most of this, i.e. have imperative state management operations (CRUD+List) exposed and generated through the CLI and then have declarative state management implemented in a tool like Terraform.