Enable building api code upon start

[janirapo]

I have setup my api using TypeScript and I am unable to startup both the frontend and the api at the same time using the swa start command, because the TypeScript code needs to be built before you can run it as JavaScript.

Instead of running func start in the api folder you should provide a way to run e.g. npm start within that folder, so that the developer can setup prestart tasks that build the code before trying to run it. My suggestion would be to add parameter --run-api, so that you could use --run-api="npm start", which would run the command in the api folder.

An alternative way could be to provide a way to run a pre-start task, so that you can build the api by separate parameter at beforehand. E.g. --build-api="npm run build", which would run the command within the api folder.

[JeffreyCA]

As a workaround I modified the build script of the root package.json so it builds both the front-end and API when you run npm run build from the root dir.

"scripts": {
    ...
    "build": "npm run build --prefix api && react-scripts build",
    ...
},