Create an implementation for common.ts that uses wasm-pack's pkg output

[mbalex99]

• Create an entry point in src/ called wasm-entry.ts that implements what the pkg output
• Ensure that yarn build-typescript creates this file appropriately in dist/
• Add the reference to the browser entry point in package.json. See here for more info

Comments

• The output of the WebAssembly entry-point can be a ES6 module. There isn't a browser that supports WebAssembly but doesn't support ES6 Modules. Customers that use webpack should be able to consume the package as a module without much hassle.