Add use_fixed_vhd_format Hyper-V ISO option

[adarobin]

I have added an option to the Hyper-V ISO builder named "azure_compatible". This will instruct the builder to create a VM with a VHD that is compatible with Azure.

Azure needs a Fixed size VHD, the default is a dynamic VHDX.

Closes #5617

[SwampDragons]

Thanks for the PR! I like this idea a lot, but I don't like the name you've given the feature; azure_compatible is not explicit and would be confusing to anyone who doesn't want to have to read source code. Can we name it something like use_vhd_format instead? We can talk in the docs about how this makes the VMs compatible with Azure. (While we're on the subject, this new feature could use some docs, too, and maybe a test or two checking the logic you've added to the config)

[SwampDragons]

Good start; See my previous comment for some change requests.
-- docs
-- tests for config logic
-- more explicit feature name.

[adarobin]

@SwampDragons Its funny you don't like the name. I had originally named the feature use_legacy_vhd, but I didn't like that name as Azure also needs a VHD file that is fixed size and not dynamic (which is the default if -Fixed is not passed to New-VHD).

This made me wonder if use_fixed_disk should be a separate option, but then that would need to be implemented for vhdx as well? I'm going to rename it to use_fixed_vhd_format for now and work on the other requested changes.

[adarobin]

@SwampDragons I have made the requested changes. I'm much more familiar with PowerShell and Python than Go so look extra hard at the tests I added. I also realized that a VHD has a different maximum size than a VHDX so I added a check for that.

[SwampDragons]

Thanks! This is definitely on my TODO list to review.

[adarobin]

@SwampDragons I rebased this in light of all the recent Hyper-V changes.

[SwampDragons]

Good idea, thanks.

this review was stale, so dismissing it.

[SwampDragons]

Thanks for this PR!

[ghost]

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