fix: Refactor LayersMap to correct old strange code behavior (#2066)

* fix: Correct flatten function in layers

- Added a test.
- Cache current image, track deletes in `whiteouts` as well as normal adds in `layers`.
- Fix ugly delete behavior of `layerHashCache`.
  Delete it when crerating a new snapshot.
- Slight cleanup in `snapshot.go`.
- Format ugly `WalkFS` function.

* fix: Add symbolic link changes  to Hasher and CacheHasher

* fix: Better log messages

* fix(ci): Integration tests

* fix(ci): Add `--no-cache` to docker builds

* fix(ci): Pass credentials for error integration test

* np: Missing .gitignore in `hack`

* np: Capitalize every log message

- Correct some linting.

* fix: Key function

- Merge only last layer onto `currentImage`.

* fix: Remove old obsolete `cacheHasher`

cmd/executor/cmd/root.go

@@ -128,7 +128,7 @@ var RootCmd = &cobra.Command{
 			if !force {
 				exit(errors.New("kaniko should only be run inside of a container, run with the --force flag if you are sure you want to continue"))
 			}
-			logrus.Warn("kaniko is being run outside of a container. This can have dangerous effects on your system")
+			logrus.Warn("Kaniko is being run outside of a container. This can have dangerous effects on your system")
 		}
 		if !opts.NoPush || opts.CacheRepo != "" {
 			if err := executor.CheckPushPermissions(opts); err != nil {
@@ -158,11 +158,11 @@ var RootCmd = &cobra.Command{
 				return
 			}
 			if strings.HasPrefix(benchmarkFile, "gs://") {
-				logrus.Info("uploading to gcs")
+				logrus.Info("Uploading to gcs")
 				if err := buildcontext.UploadToBucket(strings.NewReader(s), benchmarkFile); err != nil {
 					logrus.Infof("Unable to upload %s due to %v", benchmarkFile, err)
 				}
-				logrus.Infof("benchmark file written at %s", benchmarkFile)
+				logrus.Infof("Benchmark file written at %s", benchmarkFile)
 			} else {
 				f, err := os.Create(benchmarkFile)
 				if err != nil {
@@ -171,7 +171,7 @@ var RootCmd = &cobra.Command{
 				}
 				defer f.Close()
 				f.WriteString(s)
-				logrus.Infof("benchmark file written at %s", benchmarkFile)
+				logrus.Infof("Benchmark file written at %s", benchmarkFile)
 			}
 		}
 	},