Upload sourcemaps to Azure from CI

[pl4nty]

Allows unminifying code in Application Insights, as documented. Would make troubleshooting from logs much easier. Not sure if this is possible given that Azure (Oryx) handles the build, but worth investigating.

[ashleylamont]

I would presume Oryx would pick up that it's a Webpack/CRA installation from Node deps or that there's a Node build script, and run it that way, in which case it would all go through webpack (which is admittedly obscured by CRA) which should be generating sourcemaps already I thought, unless it was disabled, in any case it shouldn't be terribly difficult to re-enable them I think? I'll have to look into it a little

[pl4nty]

@ashleylamont yeah it generates sourcemaps, but I'm not sure how to get those from Oryx into a Blob container

[pl4nty]

After digging a bit deeper, we would need to move builds from Oryx to Actions as discussed in Azure/static-web-apps#17. I'm ok with that, would just have to be more careful when applying the 'safe to test' label - PRs could potentially access secrets during the build process.