Internalize majority of cmd package (#2533)

* internalize majority of cmd package and migrate integration tests

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* add internal api encoder

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* create internal representation of all formats

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* export capability to get default encoders

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* restore test fixtures

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

cmd/syft/internal/test/integration/regression_photon_package_test.go

@@ -0,0 +1,20 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/anchore/syft/syft/pkg"
+	"github.com/anchore/syft/syft/source"
+)
+
+func TestPhotonPackageRegression(t *testing.T) { // Regression: https://github.com/anchore/syft/pull/1997
+	sbom, _ := catalogFixtureImage(t, "image-photon-all-layers", source.AllLayersScope)
+	var packages []pkg.Package
+	for p := range sbom.Artifacts.Packages.Enumerate() {
+		packages = append(packages, p)
+	}
+
+	if len(packages) < 1 {
+		t.Errorf("failed to find packages for photon distro; wanted > 0 got 0")
+	}
+}