Update SDK to v2

[dmacvicar]

This PR updates the SDK to v2, which meant lot of porting, missing features and bubbled bugs catched by the new SDK.

Changes that were required to upgrade the SDK:

• DNS hosts is now a set and it is read from libvirt into the state
• DCHP enablement is now computed, and uses a workaround to be explicitly set or disabled by the user while being enabled by default, unfortunately, using GetOkExists for now
• cloudinit disks are read back, and a workaround (custom serial) is used to mark them as owned by the cloudinit setting. This workaround needs to be improved/cleaned up.
• Ignition provider uses the old v1 SDK and my contribution to update it to v2 has not been merged, therefore our tests refer to my upgraded fork.
• Some settings are now read back from libvirt, like firmware, nvram, cpu mode, etc.

Future work could be to port the Create/Read/etc functions to their new equivalents, which have better support for Context and Diagnostics.