rename scope to source

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

syft/source/scope.go

@@ -0,0 +1,40 @@
+package source
+
+import "strings"
+
+const (
+	UnknownScope Scope = iota
+	SquashedScope
+	AllLayersScope
+)
+
+type Scope int
+
+var optionStr = []string{
+	"UnknownScope",
+	"Squashed",
+	"AllLayers",
+}
+
+var Options = []Scope{
+	SquashedScope,
+	AllLayersScope,
+}
+
+func ParseOption(userStr string) Scope {
+	switch strings.ToLower(userStr) {
+	case strings.ToLower(SquashedScope.String()):
+		return SquashedScope
+	case "all-layers", strings.ToLower(AllLayersScope.String()):
+		return AllLayersScope
+	}
+	return UnknownScope
+}
+
+func (o Scope) String() string {
+	if int(o) >= len(optionStr) || o < 0 {
+		return optionStr[0]
+	}
+
+	return optionStr[o]
+}