osbuild-store-dump: use distrofactory instead of importing fedora

This commit removes the direct use of `pkg/distro/fedora` and
uses `distrofactory` instead. This is the more generic interface,
it also helps with PR#1563 as `pkg/distro/fedora` goes away.

Note that I did not test this but @bcl was kind enough to
mention how this is used:
```
The output from this is used in Test_upgrade in
internal/store/json_test.go, the files there are manually
created when we change the format of the store and add a new
parser to internal/store/json.go -- which hasn't happened in
a long time :)
```
I updated the cmd/README with a snippet of the above.

cmd/README

@@ -32,5 +32,6 @@ osbuild-dnf-json-tests
 osbuild-image-tests
 osbuild-koji-tests
 osbuild-mock-openid-provider
-osbuild-store-dump
 osbuild-upload-*
+
+osbuild-store-dump: the output from this is used in Test_upgrade in internal/store/json_test.go

cmd/osbuild-store-dump/main.go

@@ -12,7 +12,6 @@ import (
 	"github.com/osbuild/blueprint/pkg/blueprint"
 	"github.com/osbuild/images/pkg/arch"
 	"github.com/osbuild/images/pkg/distro"
-	"github.com/osbuild/images/pkg/distro/fedora"
 	"github.com/osbuild/images/pkg/distrofactory"
 	"github.com/osbuild/images/pkg/dnfjson"
 	"github.com/osbuild/images/pkg/manifest"
@@ -130,7 +129,7 @@ func main() {
 
 	const fedoraID = "fedora-37"
 
-	d := fedora.DistroFactory(fedoraID)
+	d := distrofactory.NewDefault().GetDistro(fedoraID)
 	a, err := d.GetArch(arch.ARCH_X86_64.String())
 	if err != nil {
 		panic(err)
@@ -154,7 +153,7 @@ func main() {
 	}
 	rpmmdCache := path.Join(homeDir, ".cache/osbuild-composer/rpmmd")
 
-	df := distrofactory.New(fedora.DistroFactory)
+	df := distrofactory.NewDefault()
 
 	s := store.New(&cwd, df, nil)
 	if s == nil {