[Az.Functions] Add support for dotnet-isolated runtime

[Francisco-Gamino]

Add support for dotnet-isolated runtime

[Francisco-Gamino]

/cc: @stefanushinardi @AnatoliB @anthonychu

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @ahmedelnably, @fabiocav.

Issue Details

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Add support for in preview dotnet-isolated runtime

Author:	Francisco-Gamino
Assignees:	Francisco-Gamino
Labels:	Functions, Service Attention
Milestone:	-

[Francisco-Gamino]

@gzuber -- Do you know why we need this work around for the dotnet-isolated runtime https://github.com/Azure/azure-cli/blob/dev/src/azure-cli/azure/cli/command_modules/appservice/custom.py#L2964?

[Francisco-Gamino]

@anthonychu -- what should it be the default OS for dotnet-isolated? Here is the current supported mapping: https://github.com/Azure/azure-powershell/blob/generation/src/Functions/custom/HelperFunctions.ps1#L13