Adding type hinting to the private message thread form build form, allowing it to be properly extended by other modules.

Fixing various bugs in the module preventing proper installation, and preventing the private message form from working

Adding history API into thread inbox, to change the URL when threads are clicked in the inbox. Setting up the inbox update to be triggered after a new post is made. Adding .active-thread class to the active thread in the inbox. Removing .unread-thread class from inbox thread when a thread is viewed. Fixing cache tag invalidation overall for inbox

adding functionality to delete private messages. This required redoing some routes, adding aacess to the threads, fixing bugs loading the wrong thread in the inbox as well as the most recent thread

Setting up inbox to only show 5 threads, cleaning up some formatting, setting up similar code for different areas to follow same logic