Pass a map <URL, handler> to createExpressApp #7
Description
The createExpressApp() function returns a function that takes an (Express) handler as argument: https://github.com/mozilla/addons-cli-utils/blob/9fd4e7b7d37022baa0ea2022fe2150d717621b3e/src/functions.ts#L65
This handler is configured to respond to POST / requests in the function. We should probably add the ability to register more than one URL/handler if this tool gets new commands and we need to expose these commands as HTTP/RPC services.
We could maybe pass a map of <URL, handler> instead (we could potentially specify the HTTP verb too).