Take image virtual size into account when creating Volumes

This is a followup to #1104

When creating new volumes on the Volume screen in Harvester, the
default size is empty, i.e. it's not pre-filled with anything at
all.  If the source is set to "VM image" we can now take the image
virtual size and use that as the default size for the volume.
Unlike when creating VMs (which always set the volume to a minimum
of 10GiB regardless of virtual size, for consistency with earlier
harvester versions), on this screen we just use the virtual size
as-is.  If the user wants to make it bigger, they can.

Related issue: harvester/harvester#4905

Signed-off-by: Tim Serong <tserong@suse.com>

pkg/harvester/edit/harvesterhci.io.volume.vue

@@ -249,7 +249,18 @@ export default {
 
       this.$set(this.value, 'spec', spec);
     },
+    updateImage() {
+      if (this.isVMImage && this.imageId) {
+        const images = this.$store.getters['harvester/all'](HCI.IMAGE);
+        const imageResource = images?.find(image => this.imageId === image.id);
+        const imageSize = Math.max(imageResource?.status?.size, imageResource?.status?.virtualSize);
 
+        if (imageSize) {
+          this.storage = `${ Math.ceil(imageSize / 1024 / 1024 / 1024) }Gi`;
+        }
+      }
+      this.update();
+    },
     generateYaml() {
       const out = saferDump(this.value);
 
@@ -300,7 +311,7 @@ export default {
           required
           :mode="mode"
           class="mb-20"
-          @input="update"
+          @input="updateImage"
         />
 
         <LabeledSelect