Add support for nested templates

[darenkeck-dev]

Add support for nested grouping of templates by allowing system types to be nested.

Updating Parser Output

templates.json should expand the SystemType object, adding a Parent field, allowing nested structures of Templates.

export interface SystemTypeN {
  description: string;
  modelicaPath: string; // Modelica fully qualified class name
  parent: string | null; // null if the root
}

Update the Client

Update the client to display nested system types.