added database connectivity MySQL

src/main/java/com/example/bookmanagement/Book.java

src/main/java/com/example/bookmanagement/BookController.java

src/main/java/com/example/bookmanagement/BookRepository.java

...ain/java/com/example/bookmanagement/SimpleController.java

src/main/resources/application.properties

src/main/resources/database.sql

src/main/resources/templates/index.html

...m/example/bookmanagement/SpringBootBootstrapLiveTest.java