feat: Add dateUpdated field to Post model and update PostController

[baserrato]

This pull request introduces several new features and improvements to the devopsknowledgeshareapi project. The most significant changes include the addition of AuthorController and AuthorService classes, new search capabilities in PostController, an update field in the Post class, and corresponding updates to the test classes.

New Classes:

• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorController.java: A new AuthorController class was added. It uses the AuthorService to handle requests to the /authors endpoint.
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorService.java: A new AuthorService class was added. It currently returns an empty list of authors.

Updates to Existing Classes:

• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/Post.java: The Post class was updated to include a dateUpdated field with corresponding getter and setter methods.
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/PostController.java: The PostController class was updated to include new search capabilities. It can now handle requests to search posts by title, first name, and link. Additionally, a PUT request handler was added to update existing posts. [1] [2]
• src/main/java/com/liatrio/dojo/devopsknowledgeshareapi/PostRepository.java: The PostRepository interface was updated to include new methods for finding posts by title, first name, and link.

Test Updates:

• src/test/java/com/liatrio/dojo/devopsknowledgeshareapi/AuthorControllerTest.java: A new test class for AuthorController was added. It currently includes a single test for the getAuthors method.
• src/test/java/com/liatrio/dojo/devopsknowledgeshareapi/PostTest.java: The PostTest class was updated to include new tests for the dateUpdated field in the Post class. [1] [2]