[interop] Add Support for Function Declarations (#392)

* Interop Gen: Support Function Declarations
Fixes #389

* code resolution

* changed primitive types from `enum` to `static const` types

* minor changes

* formatting

* resolved code issues, added test cases, and refactored primitive type handling

* Comment Resolution:

- enum switch expression refactoring
- other fixes

* completed comment resolution
17 files changed