[csx] Invalid Function can still be invoked via the Portal and returns a 202, with no indicated error

Create a bad csx function -- like below. It's got an additional parameter that doesn't correspond to any binding:

```
using System;

public static void Run(TimerInfo myTimer, ICollector output, ILogger log)
{
log.LogInformation("Hi!");
}
```

binding:
```
{
"bindings": [
{
"name": "myTimer",
"type": "timerTrigger",
"direction": "in",
"schedule": "*/10 * * * * *"
}
]
}
```

Try to invoke it. You get a 202 Accepted. And no indication of any error, but also no streaming logs. Internally, the call to invoke this is failing early because the function isn't set up correctly. But that log doesn't get caught or reported anywhere.

There's a couple issues here:
1. In the portal, there's no indication of any error during compilation. The indexing error is logged to the host, rather than the function file. I see the correct FunctionIndexingException in my host logs.
2. When attempting to invoke, a better response needs to be given. This function wasn't invoked and had an issue -- we should be reporting that somewhere.

Reproduce the invalid C# script with the extra unbound parameter and the timer binding shown in the issue, then inspect the host logs and portal invocation behavior. The work is done when indexing failures are surfaced to the portal and invoking the invalid function reports an error instead of returning 202 Accepted without logs.

Written by the indexing model from the issue text.