Add payload transform keywords and function

Add keywords: dlq, payload, transform, transforms
Add function: payload()

These support the new CREATE/DROP/SHOW PAYLOAD TRANSFORM syntax and
the payload() function for accessing HTTP request bodies in transform
SQL expressions.

Author: javier

src/grammar/functions.ts

@@ -150,6 +150,7 @@ export const functions: string[] = [
   "nvl",
   "or",
   "parquet_scan",
+  "payload",
   "permissions",
   "pg_advisory_unlock_all",
   "pg_attrdef",

src/grammar/keywords.ts

@@ -53,6 +53,7 @@ export const keywords: string[] = [
   "details",
   "disable",
   "distinct",
+  "dlq",
   "drop",
   "else",
   "enable",
@@ -132,6 +133,7 @@ export const keywords: string[] = [
   "partition",
   "partitions",
   "password",
+  "payload",
   "period",
   "permissions",
   "pivot",
@@ -178,6 +180,8 @@ export const keywords: string[] = [
   "token",
   "tolerance",
   "transaction",
+  "transform",
+  "transforms",
   "transient",
   "truncate",
   "ttl",