Allow specifying minimum image size in auroraboot raw images

[jimmykarily]

Discussion started here: https://github.com/kairos-io/kairos/pull/3154/files#r1933473895

When we create a cloud image with Auroraboot, the resulting disk image file has a recovery partition size defined by the source image size. This means, a raw image created for a "core" Kairos source image, might not fit a standard image if the user resets to such an image using reset.system.uri.

Since this flow is our recommended flow (because we want to avoid uploading all our flavors and k3s versions), we need to make sure any of our images will fit in the recovery partition.

For this reason, we will implement a flag in auroraboot that will override the image size when set. So instead of using the source image size, the define value will be used to calculate the recovery partition size (and the state one upon booting but that should already happen I guess, needs checking).