Tutorial update

[robertmcnees]

I followed along with the guide and made some changes that will hopefully allow for a better user experience.

From a technical perspective, I updated the tutorial from Boot 2.3 to Boot 3.2. This necessitated a change from Java 8 to Java 17, as well as a package name change from javax to jakarta. Other than the package name changes, no other functionality changes were required. I also updated the maven wrapper.

In the README there were several changes to the presentation of the material, but no change to the teaching material:

• I made the distinction between building a project from scratch and looking to the solution repository. The solution repository uses modules, in order to help users build on multiple learning elements in the tutorial. I inserted headers so that the user knows when one module (and thus one concept) stops and the next begins.
• I used collapsible blocks for almost all code and output. These blocks default to open, so there should be no immediate impact to the user. I found when going through the tutorial that I was frequently scrolling through large code blocks and I think there is value in being given the option to collapse them to bring the teachings closer together.

This PR should fix issues #117 #116 #96 #101.