Migration to Azure.Identity

[thompson-tomo]

The following dependencies have been deprecated

• Microsoft.Azure.Services.AppAuthentication
• Microsoft.Rest.ClientRuntime.Azure.Authentication

And as such the library should transition to

• Azure.Identity

With the affected packages being

• FluentStorage.Azure.DataLake

[robinrodricks]

I had investigated this before but the new Identity system has many breaking changes and it caused a lot of headache.