Changes to SQL file to support Item categories, Item class. Incomplete controller code.

phase 1.sql

...example/accessingdatamysql/item/CustomItemRepository.java

src/main/java/com/example/accessingdatamysql/item/Item.java

...a/com/example/accessingdatamysql/item/ItemController.java

...a/com/example/accessingdatamysql/item/ItemRepository.java

src/main/resources/application.properties