Extract sdk into its own lib

This had some side effects:

 - Have to add some utils from the kairos/machine modules, which IMHO
   should not be there, they should be here if the are generic enough
 - Dropping the sdk dir, just have the modules in the root dir

Signed-off-by: Itxaka <itxaka.garcia@spectrocloud.com>

system/options.go

@@ -0,0 +1,30 @@
+package system
+
+import (
+	"github.com/hashicorp/go-multierror"
+)
+
+type Changeset []func() error
+
+func (c *Changeset) Add(f func() error) {
+	*c = append(*c, f)
+}
+
+type Option func(c *Changeset) error
+
+func Apply(opts ...Option) error {
+
+	c := &Changeset{}
+	for _, o := range opts {
+		if err := o(c); err != nil {
+			return err
+		}
+	}
+
+	var err error
+	for _, f := range *c {
+		err = multierror.Append(f())
+	}
+
+	return err
+}