[FEATURE] Make startup failures more transparent in Azure

#### What problem would the feature you're requesting solve? Please describe.
Startup failures have always felt needlessly hard to troubleshot in deployed functions. In particular trying to implement eager settings validation is a pain as it's not readily apparent why the startup fails even when there's a very clear exception message. Currently these exceptions are hidden in some troubleshooting page with no clear indication that an error has ocurred outside of that page.

#### Describe the solution you'd like
Whenever a startup exception happens the overview page should make it obvious that there's been an error, possibly including a message indicating that an exception has happened with a link to see the full details.

#### Additional context
Here's a sample view of how such startup failure looks right now. Just an empty function app without any indication that a failure has ocurred.