RHEL-90: introduce default image config data structure

Introduce a new data structure `ImageConfig` holding the default OS
configuration applied when building an image. The structure can be used
to hold the default image configuration on the distribution level with
possible overrides defined on the image-type level.

As a starting point, move hard-coded default values and configuration
common for `osPipeline`, `ec2BaseTreePipeline` and `ostreeTreePipeline`
to the distribution and image-type default image configuration. This is
preparing the ground for merging all of these three pipeline functions
into `osPipeline`, which will produce the appropriate OS pipeline based
on the image-type configuration and the fact if it is rpmOstree or not.

Regenerate affected EC2 and AMI manifests. There is however no change in
the resulting image configuration and image-info report.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

internal/distro/image_config.go

@@ -0,0 +1,48 @@
+package distro
+
+import "github.com/osbuild/osbuild-composer/internal/osbuild2"
+
+// ImageConfig represents a (default) configuration applied to the image
+type ImageConfig struct {
+	Timezone            string
+	TimeSynchronization *osbuild2.ChronyStageOptions
+	Locale              string
+	Keyboard            *osbuild2.KeymapStageOptions
+	EnabledServices     []string
+	DisabledServices    []string
+	DefaultTarget       string
+	Sysconfig           []*osbuild2.SysconfigStageOptions
+}
+
+// InheritFrom inherits unset values from the provided parent configuration and
+// returns a new structure instance, which is a result of the inheritance.
+func (c *ImageConfig) InheritFrom(parentConfig *ImageConfig) *ImageConfig {
+	finalConfig := ImageConfig(*c)
+	if parentConfig != nil {
+		if finalConfig.Timezone == "" {
+			finalConfig.Timezone = parentConfig.Timezone
+		}
+		if finalConfig.TimeSynchronization == nil {
+			finalConfig.TimeSynchronization = parentConfig.TimeSynchronization
+		}
+		if finalConfig.Locale == "" {
+			finalConfig.Locale = parentConfig.Locale
+		}
+		if finalConfig.Keyboard == nil {
+			finalConfig.Keyboard = parentConfig.Keyboard
+		}
+		if finalConfig.EnabledServices == nil {
+			finalConfig.EnabledServices = parentConfig.EnabledServices
+		}
+		if finalConfig.DisabledServices == nil {
+			finalConfig.DisabledServices = parentConfig.DisabledServices
+		}
+		if finalConfig.DefaultTarget == "" {
+			finalConfig.DefaultTarget = parentConfig.DefaultTarget
+		}
+		if finalConfig.Sysconfig == nil {
+			finalConfig.Sysconfig = parentConfig.Sysconfig
+		}
+	}
+	return &finalConfig
+}