Add JS code generation for ID regular expressions

[rsek]

These are already generated for (and made available in) the JSON schema. But offering them as JS RegExp objects offers a few benefits to folks using the language:

• don't have to load and traverse the Datasworn schema (which is pretty big) to get them
• provide features like named capture groups; the group names can correspond to the parts of the type prefix

This is mainly a matter of adding another script to Node package codegen; most of the required parts already exist. I think it's a good candidate for v0.1.0.

[rsek]

Deferring this until after v0.1.0. I want to give some more thought to how this could be generalized in code generation.