Adds azureProperty property to handle backward compatibility when using the isBinary property

[SayakMukhopadhyay]

Closes #494

[Flydiverny]

I'm not sure I understand the intent #494 references #311 which talks about property, this is true for all cases of returning binary data from a secret backend (some require isBinary to be set, some can detect automatically).

apiVersion: kubernetes-client.io/v1
kind: ExternalSecret
metadata:
  name: hello-service
spec:
  ...
  data:
    - key: hello-service/credentials
      name: password
      property: password # <--- this is unsupported with `isBinary`
      isBinary: true

I'm not sure what issue or use case you are trying to cover, would be great on you could elaborate.

It's correct that the Azure backend currently doesn't have feature parity with other backends outside of isBinary usage, there's some info in #460 which tries to resolve this allowing property to be used as expected (when not using isBinary)

[Flydiverny]

Closing this until further discussion takes place.