[Feature Request] Make creating new virtual hard disk optional when creating a new VM

[flanter21]

I wanted to run Fedora 40 in UTM. As there is no arm64 ISO version right now, I downloaded the raw.xz and converted it to qcow2. When creating the VM, it asked me to give a size for the virtual hard disk. I didn't want to do that as I just wanted to run the qcow2, but it forced me to and I had to delete it after. It's a minor issue, but hopefully a minor fix?

I suggest this could be solved by adding a checkbox or a skip button to this step.

[ideologysec]

Another possibility would be to add an option that allows for specifying an existing boot image, instead of a boot ISO.