generate meta tables for meta evaluations; use to table-drive ctrl msg serialization, deserialization, meta eval type info generation, and info <-> serialized eval path

src/dbg_engine/dbg_engine_core.h

@@ -233,6 +233,7 @@ struct D_CmdParams
   CTRL_Handle thread;
   CTRL_Handle entity;
   CTRL_HandleList processes;
+  String8 string;
   String8 file_path;
   TxtPt cursor;
   U64 vaddr;