migrate json schema generation (#4270)

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

internal/sourcemetadata/generated.go

@@ -0,0 +1,10 @@
+// DO NOT EDIT: generated by internal/sourcemetadata/generate/main.go
+
+package sourcemetadata
+
+import "github.com/anchore/syft/syft/source"
+
+// AllTypes returns a list of all source metadata types that syft supports (that are represented in the source.Description.Metadata field).
+func AllTypes() []any {
+	return []any{source.DirectoryMetadata{}, source.FileMetadata{}, source.ImageMetadata{}, source.SnapMetadata{}}
+}