Allow to target resources when running local-preview

[tomasmik]

This was suggested by people in the issue comments. I tested it and it works just fine. I've updated the resources:

--- a/main.tf
+++ b/main.tf
@@ -1,18 +1,18 @@
 resource "random_string" "random" {
-  length           = 12
+  length           = 112
   special          = true
   override_special = "/@£$"
 }

 resource "random_string" "random2" {
-  length           = 11
+  length           = 10
   special          = true
   override_special = "/@£$"
 }


 resource "random_string" "random3" {
-  length           = 13
+  length           = 19
   special          = true
   override_special = "/@£$"
 }

When calling spc stack local-preview -target="random_string.random,random_string.random2", my plan looks like this: