Implement Hypervisor field on instances

[nesitor]

Problem: Instances with QEMU hypervisor cannot be created.

Solution: Implement hypervisor field into create_instance method.

[github-actions]

• Introduces new feature: 'HypervisorType'
• Changes default value for hypervisor parameter in function 'create_instance'
• Modifies multiple files (authenticated_http.py)
• Potential impact on codebase could be high due to extensive changes and deep understanding of project architecture required

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[hoh]

Nice, can we add a unit test to prevent regressions ?

[hoh]

Tests are failing due to isort, can you fix that ?

[MHHukiewitz]

And now black is failing ^^'

[nesitor]

And now black is failing ^^'

I already passed black on whole src folder, but in this project also we check the tests and the examples folder. Already fixed that issues.

[hoh]

Tests fail due to:

>       assert instance_message.content.hypervisor == HypervisorType.firecracker
E       AttributeError: 'InstanceContent' object has no attribute 'hypervisor'

[MHHukiewitz]

LGTM