(Azure) Resolve invalid JSON Object under properties field

[d1g1tal-lore-34]

What does this PR do?

Added a function call fixPropertiesJsonString, that works on converting malformed JSON String that is part of the properties field into a proper JSON object. This issue is documented in the follow Microsoft Post.

Motivation

This will allow Datadog Log Processor to extract the proper message and log level field. This fixes issue #1014

Testing Guidelines

It has been tested in two manners:

• Tested in my Datadog Instance
• Test cases have been created under EventhubLogHandler Fix Properties Json String

Additional Notes

This issue is documented in the follow Microsoft Post.

Types of changes

• Bug fix

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)
• This PR passes the unit tests
• This PR passes the installation tests (ask a Datadog member to run the tests)