Add jdbc-vs-jpa module: Spring Data JDBC vs JPA on a shared Order aggregate

Same Customer/Order/OrderItem domain modelled with Hibernate/Spring Data JPA and
Spring Data JDBC side by side, both running through a shared StatementLoggingDataSource
so SQL-statement counts are directly comparable. 11 tests, 11 captured transcripts,
6 doc chapters. Companion repo for the ankurm.com article on when to drop the ORM.

jdbc-vs-jpa/docs/output/02-n-plus-one.txt

@@ -0,0 +1,13 @@
+Scenario: findAll() for 3 orders (2 items each), then read .getItems().size()
+on each in a loop — the pattern that looks completely ordinary in a service
+method.
+
+ 1. select o1_0.id,o1_0.customer_id,o1_0.version from jpa_order o1_0
+ 2. select i1_0.order_id,i1_0.id,i1_0.quantity,i1_0.sku from jpa_order_item i1_0 where i1_0.order_id=?
+ 3. select i1_0.order_id,i1_0.id,i1_0.quantity,i1_0.sku from jpa_order_item i1_0 where i1_0.order_id=?
+ 4. select i1_0.order_id,i1_0.id,i1_0.quantity,i1_0.sku from jpa_order_item i1_0 where i1_0.order_id=?
+
+total statements: 4
+
+SELECT statements observed: 4  (1 for the orders themselves + 1 per order for
+its lazily-loaded items = N+1, here 1 + 3 = 4)