Determine the general approach for WASM to JS binding generation + demonstrate with a simple function export

[ianthetechie]

• Task 1: determine what we will use for binding generation. I mentioned on our first intro call that wasm-bindgen seems the likely candidate, but feel free to do some research on alternatives.
• Task 2: demonstrate that it works with a simple function export and a test page using Javascript to call the WASM function. (Note that this test code doesn't need to be merged into the project, but we do need to have a quick demo + code to verify that the approach works).

[ianthetechie]

I would suggest the following as a path forward once #120 is merged.

First, build a minimal POC: Add an extremely simple function (add two numbers?) to lib.rs and export it with wasm-bindgen. Then build a very simple webpage that loads the module and calls the function with JS and does a console log or something. It does not have to be pretty; just demonstrate that it's working.

I would suggest using a conditional dependency and attributes as shown at the end of this page: https://rustwasm.github.io/docs/wasm-bindgen/reference/rust-targets.html. This way we keep binary size smaller on other platforms.

From there, I would suggest that OsrmResponseParser is the easiest "real" thing to start with. It is very easy to test, since the core function is parsing string input and parsing it into a Route. I'll create a task for that.