[Linked fields] Add Linked Field as custom field type (#1206)

* Add linked fields

* Update to use Field.linkedId

* Update jslib

src/locales/en/messages.json

@@ -166,6 +166,10 @@
   "cfTypeBoolean": {
     "message": "Boolean"
   },
+  "cfTypeLinked": {
+    "message": "Linked",
+    "description": "This describes a field that is 'linked' (related) to another field."
+  },
   "remove": {
     "message": "Remove"
   },
@@ -311,6 +315,9 @@
   "lastName": {
     "message": "Last Name"
   },
+  "fullName": {
+    "message": "Full Name"
+  },
   "address1": {
     "message": "Address 1"
   },