Azure-functions-worker

1. Fix the **'EnumTypeWrapper' object has no attribute 'System'** issue for customers who use **protobuf < 3.8.0** package. (https://github.com/Azure/azure-functions-python-worker/pull/725)
- This issue is caused by https://github.com/protocolbuffers/protobuf/issues/6028
- The Azure Functions Python Worker has a dependency on **protobuf >= 3.12.0** and previously we're using a new syntax for [referencing protobuf enum class](https://github.com/Azure/azure-functions-python-worker/blob/1.1.3/azure_functions_worker/dispatcher.pyL173).
- This fix ensure our worker will still function under old protobuf version.
2. Fix an issue where **EventHubEvent.metadata** and **ServiceBusMessage.metadata** are not accessible from Python functions.

- [Hotfix] Fix an issue where the dispatcher cannot be found ("no currently running Dispatcher is found") due to asyncio event loop collision with third-party libraries.

[703] Hotfix - issue found which prevent workload > 4MB.

* Update azure-functions library to 1.2.1 with support for EventGrid output binding.
* Minor fixes
* Drop GRPC message size limitation (632)
* Improve logging in python worker (637)
* Move implicit output bindings serialization logic to Python library (643)
* Adding better troubleshooting messaging (665)

2. Fix an issue where iothub metadata are missing in the EventHub trigger [azure-functions 42](https://github.com/Azure/azure-functions-python-library/pull/42)
3. Fix an issue where cardinality is not handled correctly in EventHub when setting `cardinality = 'many'`
4. Fix an issue where current working directory is not pointing to project root in Linux Consumption apps [613](https://github.com/Azure/azure-functions-python-worker/pull/613)
5. Add WSGI support [azure-functions 45](https://github.com/Azure/azure-functions-python-library/pull/45)