Provide IDE-like experience for viewing/editing Node.js functions in the portal

Updated AF tools allow to create TypeScript-template for Azure Functions in VSCode, that is great.

1. **Displaying files from the `/dist` folder**
The structure of the project suggests that after ts-files are compiled, the output js-files are store in the `/dist` folder.
```js
{
"compilerOptions": {
"module": "commonjs",
"target": "es2017",
"outDir": "dist",
"rootDir": ".",
"sourceMap": true,
"strict": false
}
}
```
The `function.json` file in the function folder also references to that `dist` folder. 👍
The portal in the editing interface by default opens files from the `dist` folder. 👍

But when I go to the "View files" tab, I can't find the source index.js file. ☹

2. **Recompile `ts` files through the portal.**
It would be helpful to automatically compile/recompile `.ts`-files if I'm able to edit them through the portal. But probably, I don't want to install tsc on the app level. ☹

I know that it is not so easy to implement it without complicating other things.. But the current experience is somehow incomplete. You allow editing files, but it makes no sense, as they are not compiled.

3. I understand that it is up to the developer to figure out such things, but the node-version that is used in AF at least supports ES2018, and the default target version for TS in the template is ES2016. It seems like a common default across the industry, but it would be helpful to expose somehow to developers, that they can level up target version up to ES2018 (e.g., in docs or in comments in the template).