Use easy-batch's reader, processor, and writer classes

[CXwudi]

• no spring-batch, in spring-batch, you need a job repo to store steps
• with easy-batch, follow How to handle error path with easy-batch #10 on how to handle exceptions in intermedium steps and in the writing step
• don't use easy-batch JobBuilder and JobExecutor, instead, we run the reader, all processors, and writer ourselves, using our favourite framework (currently using kotlin coroutine for parallel processing, and simply forEach for iterative processing)

[CXwudi]

At this stage, we are pretty sure we are using only the three interfaces