1577 spdxlicense generate (#1691)

Update the license_list.go to have more permissible inputs for greater SPDXID matching.
EX:
GPL3 gpl3 gpl-3 and GPL-3 can all map to GPL-3.0-only

By moving all strings to lower and removing the "-" we're able to return valid SPDX license ID for a greater diversity of input strings.
---------

Signed-off-by: Christopher Phillips <christopher.phillips@anchore.com>

syft/formats/common/cyclonedxhelpers/licenses.go

@@ -10,14 +10,21 @@ import (
 func encodeLicenses(p pkg.Package) *cyclonedx.Licenses {
 	lc := cyclonedx.Licenses{}
 	for _, licenseName := range p.Licenses {
-		if value, other, exists := spdxlicense.ID(licenseName); exists {
+		if value, exists := spdxlicense.ID(licenseName); exists {
 			lc = append(lc, cyclonedx.LicenseChoice{
 				License: &cyclonedx.License{
-					ID:   value,
-					Name: other,
+					ID: value,
 				},
 			})
+			continue
 		}
+
+		// not found so append the licenseName as is
+		lc = append(lc, cyclonedx.LicenseChoice{
+			License: &cyclonedx.License{
+				Name: licenseName,
+			},
+		})
 	}
 	if len(lc) > 0 {
 		return &lc

syft/formats/common/spdxhelpers/license.go

@@ -39,12 +39,12 @@ func License(p pkg.Package) string {
 
 func parseLicenses(raw []string) (parsedLicenses []string) {
 	for _, l := range raw {
-		if value, other, exists := spdxlicense.ID(l); exists {
-			parsed := value
-			if other != "" {
-				parsed = spdxlicense.LicenseRefPrefix + other
-			}
-			parsedLicenses = append(parsedLicenses, parsed)
+		if value, exists := spdxlicense.ID(l); exists {
+			parsedLicenses = append(parsedLicenses, value)
+		} else {
+			// we did not find a valid SPDX license ID so treat as separate license
+			otherLicense := spdxlicense.LicenseRefPrefix + l
+			parsedLicenses = append(parsedLicenses, otherLicense)
 		}
 	}
 	return