fix: use "contents" field and remove "fullText" license field (#3857)

---------
Signed-off-by: Christopher Phillips <32073428+spiffcs@users.noreply.github.com>

syft/format/syftjson/test-fixtures/snapshot/TestDirectoryEncoder.golden

@@ -1,7 +1,7 @@
 {
  "artifacts": [
   {
-   "id": "cf21bacaa74c8c08",
+   "id": "4dd25c6ee16b729a",
    "name": "package-1",
    "version": "1.0.1",
    "type": "python",

syft/format/syftjson/test-fixtures/snapshot/TestEncodeFullJSONDocument.golden

@@ -1,7 +1,7 @@
 {
  "artifacts": [
   {
-   "id": "783177db0211edb6",
+   "id": "fba4ca04d4906f25",
    "name": "package-1",
    "version": "1.0.1",
    "type": "python",

syft/format/syftjson/test-fixtures/snapshot/TestImageEncoder.golden

@@ -1,7 +1,7 @@
 {
  "artifacts": [
   {
-   "id": "2d8996d6f81313df",
+   "id": "72567175418f73f8",
    "name": "package-1",
    "version": "1.0.1",
    "type": "python",

syft/format/syftjson/to_format_model.go

@@ -230,12 +230,11 @@ func toLicenseModel(pkgLicenses []pkg.License) (modelLicenses []model.License) {
 
 		modelLicenses = append(modelLicenses, model.License{
 			Value:          l.Value,
-			FullText:       l.FullText,
 			SPDXExpression: l.SPDXExpression,
+			Contents:       l.Contents,
 			Type:           l.Type,
 			URLs:           urls,
 			Locations:      locations,
-			Contents:       l.Contents,
 		})
 	}
 	return