Interning serv4 strings

[metalgearsloth]

So at one point I checked and there was a lot of memory allocated for stuff like ambientsound strings. Might be better to either just globally use string interning for the datafields or alternatively make a separate serializer for it.

[moonheart08]

As this is sourcegenned now we could likely just add a new datafield attribute or property that tells the serializer to call string.Intern() on the string.

[metalgearsloth]

Apparently string.Intern is omega-slow and FrozenDictionary might end up better so would just need to make a new manager for it and then lock it at some point.