Serialize UniqueId properties + support setting default property valu…

…e in patches (#437)

patches/instance.yml

@@ -1,22 +1,25 @@
 Change:
   Instance:
-    # UniqueId properties might be random everytime Studio saves a place file
-    # and don't have a use right now outside of packages, which Rojo doesn't
-    # account for anyway. They generate diff noise, so we shouldn't serialize
-    # them until we have to.
+    # UniqueId is randomized per Studio load, but that's not a useful default.
+    # Rather than getting the default from Studio, we manually specify it here
+    # instead. The all-zero UniqueId can appear in files multiple times so it's
+    # the only default value that makes sense.
     UniqueId:
-      Serialization:
-        Type: DoesNotSerialize
+      DefaultValue:
+        UniqueId: "00000000000000000000000000000000"
     HistoryId:
-      Serialization:
-        Type: DoesNotSerialize
+      DefaultValue:
+        UniqueId: "00000000000000000000000000000000"
 
     archivable:
       AliasFor: Archivable
     Archivable:
       Serialization:
         Type: SerializesAs
         As: archivable
+      # Archivable has no default value recorded but we need it to be true
+      DefaultValue:
+        Bool: true
 
     # Attributes serialize as a BinaryString with a strange name, but we want to
     # refer to them with a different name.

patches/lua-source-container.yml

@@ -1,10 +1,13 @@
 Change:
   LuaSourceContainer:
     # ScriptGuid is randomly generated everytime a script is saved from Studio
-    # and it makes no sense for us to write it ourselves at this moment.
+    # which means that its default would change every time a database was
+    # generated. To get around this, we need to override the default. Roblox
+    # generates a new ScriptGuid if the one in a file is an empty string, so
+    # setting the default to be an empty string is a reasonable default. 
     ScriptGuid:
-      Serialization:
-        Type: DoesNotSerialize
+      DefaultValue:
+        String: ""
 
   Script:
     Source: