Add iso builder

This adds a new package for the iso builder run directly on go.
This is extracted from the original elemental-cli and then from the now
build-less kairos-agent

This uses no deps on elemental, only deps are on kairos-agent for the
config stuff mainly.

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

tools-image/enki/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "github.com/kairos-io/enki/cmd"
+
+func main() {
+	cmd.Execute()
+}