6.13 Exercise This exercise combines the ideas from sections 6.9 and 6.10. You will create a simple guest book with PHP that allows the users to post comments and upload image files to the server and retrieve the data from the server. First, write an HTML form that allows the user to enter a name, comments, and upload an image file. Your comments: Upload file: No file selected. The user can either submit data, or view all previous posts if any. When the submit button is clicked, the data should be saved to an external text file and a feedback is displayed. When the view button is clicked, the output will look like the following: Your comments: Upload file: Alice This is fun. Bob PHP is fun..