fix(indexes): add indexes to trans_id columns

Many of our queries use the `trans_id` for convenience .. it's easier than
shipping the record_uuid to/from the client.  It's important to have an
index on it to speed up queries for the trial balance and so on.

Contributes to #1388.

server/models/schema.sql

@@ -761,6 +761,7 @@ CREATE TABLE `general_ledger` (
   KEY `cc_id` (`cc_id`),
   KEY `pc_id` (`pc_id`),
   INDEX `trans_date` (`trans_date`),
+  INDEX `trans_id` (`trans_id`),
   INDEX `record_uuid` (`record_uuid`),
   INDEX `reference_uuid` (`record_uuid`),
   INDEX `entity_uuid` (`entity_uuid`),
@@ -1304,6 +1305,7 @@ CREATE TABLE `posting_journal` (
   KEY `cc_id` (`cc_id`),
   KEY `pc_id` (`pc_id`),
   INDEX `trans_date` (`trans_date`),
+  INDEX `trans_id` (`trans_id`),
   INDEX `record_uuid` (`record_uuid`),
   INDEX `reference_uuid` (`record_uuid`),
   INDEX `entity_uuid` (`entity_uuid`),