feat: Add keywords for parallel execution grammar (#90)

Add tab completion for new keywords introduced for parallel execution. PARALLEL, EXECUTION, and PARALLEL_EXECUTION

Author: colinbarry

src/utils/constants.hpp

@@ -90,6 +90,7 @@ static const std::string kMultilinePrompt = "       -> ";
     "ENUM",
     "ENUMS",
     "EXECUTE",
+    "EXECUTION",
     "EXPLAIN",
     "FAILOVER",
     "FOR",
@@ -133,6 +134,8 @@ static const std::string kMultilinePrompt = "       -> ";
     "MULTI_DATABASE_EDIT",
     "MULTI_DATABASE_USE",
     "ON_DISK_TRANSACTIONAL",
+    "PARALLEL",
+    "PARALLEL_EXECUTION",
     "PASSWORD",
     "PORT",
     "PRIVILEGES",