feat: Add dateUpdated field and methods to Post class

[baserrato]

This pull request introduces several changes to the com.liatrio.dojo.devopsknowledgeshareapi package to improve the functionality and test coverage of the application. The most significant changes include the addition of the AuthorController and AuthorService classes, updates to the Post and PostController classes, and the creation of AuthorControllerTest and updates to PostTest.

Additions to the application:

• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorController.java: A new AuthorController class was added to handle HTTP requests related to authors. It includes a getAuthors method that fetches all authors and returns them with an HTTP status of OK.
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorService.java: The AuthorService class was added to handle operations related to authors. It includes a getAllAuthors method that fetches all authors from the AuthorRepository.

Updates to existing classes:

• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/Post.java: The Post class was updated to include a dateUpdated field, along with its corresponding setter and getter methods.
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/PostController.java: The PostController class was updated to include exception handling in the post method and a new putPost method to update a post given its ID and new details.
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/PostRepository.java: The PostRepository interface was updated to include methods for finding posts by title, first name, and link.

Testing improvements:

• src/test/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorControllerTest.java: The AuthorControllerTest class was added to test the getAuthors method in the AuthorController class.
• src/test/java/com/liatrio/dojo/devopsknowledgeshareapi/PostTest.java: The PostTest class was updated to include tests for the setDateUpdated and getDateUpdated methods in the Post class.