Add ability to scan snaps (as a source) (#3929)

syft/source/snap_metadata.go

@@ -0,0 +1,23 @@
+package source
+
+import "github.com/anchore/syft/syft/file"
+
+type SnapMetadata struct {
+	// Summary is a brief description of the snap package
+	Summary string `yaml:"summary" json:"summary,omitempty"`
+
+	// Base is the base snap this package builds upon
+	Base string `yaml:"base" json:"base,omitempty"`
+
+	// Grade is the development stage (stable, candidate, beta, edge)
+	Grade string `yaml:"grade" json:"grade,omitempty"`
+
+	// Confinement is the security isolation level (strict, classic, devmode)
+	Confinement string `yaml:"confinement" json:"confinement,omitempty"`
+
+	// Architectures are the supported CPU architectures
+	Architectures []string `yaml:"architectures" json:"architectures,omitempty"`
+
+	// Digests are hashes of the snap squashfs files
+	Digests []file.Digest `yaml:"digests" json:"digests,omitempty"`
+}