AppConfigurationPushTask: Handle null values in Configuration file

[MaryanneNjeri]

When null values are present in the json configuration file, the task will fail with the error "Cannot convert undefined or null to object"

We should have an update to handle null values

[zhenlan]

@MaryanneNjeri please add details to the issue.

[MaryanneNjeri]

Issue is resolved in the latest version of the AppConfigurationPush task version 7.0.0