consider switch from JSON to structured TypeScript data files

[psnider]

Configuration files can become complex,
and they would benefit from the typing that TypeScript provides.

Investigate a general method for loading data from modules instead of from JSON.
These modules could then be written in TypeScript,
so structural and type errors would be caught.

[psnider]

Such an approach might also support variables in values to simplify expressing relationships between like things.

For example, when many URLs share the same base, that can be put in a variable and used in the URL values. For example:

var BASE_URL = "http://localhost:4000/api"
export var CONFIG = {
    serviceA: {
        url: `${BASE_URL}/a`
    },
    serviceB: {
        url: `${BASE_URL}/b`
    }
}