Support imports

[dyst5422]

Supporting imports is likely to be a really tricky thing. We need to be able to resolve the imports PRIOR to type checking and retrieve them at that point for compilation (with a caller provided resolver/loader). This likely means pre-parsing the file into an AST to grab import statements and resolve them. I don't think there are any explicit security concerns here, but we should think about it.

[dyst5422]

Going to take a stab at this in the next week or so after a conversation with @JoelCourtney that more comprehensive support for full filesystem feature set is desired