Updated Json extension class to handle deeply nested object and array

[timayabi2020]

Fixes #3157, #3158, #3159 and #3160

Files changed

1. JsonExtenstions file updated to handle deeply nested json objects and arrays.
2. JsonExtensionTest file updated with test scenarios to validate the above change.

Example of affected cmdlet is ```Send-MgUserMail`` as reported by customer. After this change, the cmdlet should be able to process and send attachments.