Refactor source API (#1846)

* refactor source API and syft json source block

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* update source detection and format test utils

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* generate list of all source metadata types

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

* extract base and root normalization into helper functions

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

* preserve syftjson model package name import ref

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

* alias should not be a pointer

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

---------

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

syft/internal/fileresolver/container_image_squash_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/scylladb/go-set/strset"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -513,6 +514,26 @@ func Test_imageSquashResolver_resolvesLinks(t *testing.T) {
 
 }
 
+func compareLocations(t *testing.T, expected, actual []file.Location) {
+	t.Helper()
+	ignoreUnexported := cmpopts.IgnoreUnexported(file.LocationData{})
+	ignoreMetadata := cmpopts.IgnoreFields(file.LocationMetadata{}, "Annotations")
+	ignoreFS := cmpopts.IgnoreFields(file.Coordinates{}, "FileSystemID")
+
+	sort.Sort(file.Locations(expected))
+	sort.Sort(file.Locations(actual))
+
+	if d := cmp.Diff(expected, actual,
+		ignoreUnexported,
+		ignoreFS,
+		ignoreMetadata,
+	); d != "" {
+
+		t.Errorf("unexpected locations (-want +got):\n%s", d)
+	}
+
+}
+
 func TestSquashResolver_AllLocations(t *testing.T) {
 	img := imagetest.GetFixtureImage(t, "docker-archive", "image-files-deleted")