osbuild: update rpm stage with new options

- db path: set alternative rpm database path [1]
- ostree-booted: create the /run/ostree-booted marker which marks an
  install as ostree.  Install-time scripts in packages use this marker
  to treat ostree installations differently.

[1] https://github.com/osbuild/osbuild/pull/666
[2] https://github.com/osbuild/osbuild/pull/1085

internal/osbuild/rpm_stage.go

@@ -5,6 +5,9 @@ import (
 )
 
 type RPMStageOptions struct {
+	// Use the given path as RPM database
+	DBPath string `json:"dbpath,omitempty"`
+
 	// Array of GPG key contents to import
 	GPGKeys []string `json:"gpgkeys,omitempty"`
 
@@ -15,6 +18,9 @@ type RPMStageOptions struct {
 	DisableDracut bool `json:"disable_dracut,omitempty"`
 
 	Exclude *Exclude `json:"exclude,omitempty"`
+
+	// Create the '/run/ostree-booted' marker
+	OSTreeBooted *bool `json:"ostree_booted,omitempty"`
 }
 
 type Exclude struct {