#2673: feat: Microservice pattern: Polling publisher #3243 (#3292)

* added new microservice pattern polling-publisher, created folder structure, README.md & App.java

* added two service polling service & publisher service to handle two different operation & prepared initial skeleton

* polling-publisher service implementation

* fixed checkstyle errors

* subscriber-service implementation

* added entry point for subscriber service & unit test-case

* added unit test-case for DataSourceService class

* resolved dependency & structured classes

* implemented Data repository, DataSource Service & added unittest-case & implemented polling-service microservice

* implemented subscriber microservice using kafkaConsumer

* Fixed Kafka bug & added a controller to send message using API

* Fixed subscriber-service & updated pom.xml

* Fixed topic name

* added new listener for other topic

* updated all README.md

* added description on both application.yaml file

* added scope before class definition in Test classes & removed duplicate dependency from pom.xml & added required one

* added polling-publisher module in pom.xml

* Updated README.md file based on new template

* improved the README.md file & fixed it's format

* deleted unnecessary README.md files

* fixed the printing statements & used log function

* used logger to print statement

* addressed review comment: removed unnecessary dependency

* addressed review comment