Redo how to handle stale dangling files (#7171)

foo.CORRUPTED should never be created because when
multiple sets are involved we would hash the file
to wrong a location, this PR removes the code.

But allows DeleteBucket() to work properly to delete
dangling buckets/objects. Also adds another option
to Healing where a user needs to specify `--remove`
such that all dangling objects will be deleted with
user confirmation.

cmd/fs-v1_test.go

@@ -390,7 +390,7 @@ func TestFSHealObject(t *testing.T) {
 	defer os.RemoveAll(disk)
 
 	obj := initFSObjects(disk, t)
-	_, err := obj.HealObject(context.Background(), "bucket", "object", false)
+	_, err := obj.HealObject(context.Background(), "bucket", "object", false, false)
 	if err == nil || !isSameType(err, NotImplemented{}) {
 		t.Fatalf("Heal Object should return NotImplemented error ")
 	}