ScriptHost stopped after WebHostRpcWorkerChannelManager stopped

https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script.WebHost/WebHostServiceCollectionExtensions.cs#L130

This can lead to a "Did not find initialized language worker" failure of a function execution for languages with webhost level workers.

Order of events:
- Execution begins for function X
- StopApplication() from somewhere
- Web host level channels stopped [here](https://github.com/Azure/azure-functions-host/blob/f987062b51d36b2a66f8bb2f1aeae9a4012d48ed/src/WebJobs.Script/Workers/Rpc/RpcInitializationService.cs#L79)
- Execution continues... does not find initialized language workers
- ScriptHost stopped [here](https://github.com/Azure/azure-functions-host/blob/f987062b51d36b2a66f8bb2f1aeae9a4012d48ed/src/WebJobs.Script.WebHost/WebJobsScriptHostService.cs#L379) which would prevent the "did not find initialized language workers"

Applicable to java always. Applicable to python always in production. Applicable to node in production (with placeholders)