disk: CreatePartitionTable can return errors now

Modify the signature of `CreatePartitionTable` so that it is
possible to return errors from the function. This is not yet
used, but will be in the near future. Change all call sites
accordingly: in most cases we can just bubble up the error.

internal/disk/disk_test.go

@@ -44,7 +44,8 @@ func TestDisk_DynamicallyResizePartitionTable(t *testing.T) {
 	// math/rand is good enough in this case
 	/* #nosec G404 */
 	rng := rand.New(rand.NewSource(0))
-	pt = disk.CreatePartitionTable(mountpoints, 1024, &pt, rng)
+	pt, err := disk.CreatePartitionTable(mountpoints, 1024, &pt, rng)
+	assert.NoError(t, err)
 	assert.GreaterOrEqual(t, expectedSize, pt.Size)
 }