Linking archive loading to GUI

I first setup the archive_handeler package to be importable. I made a mistake and accidentally setup the package imports in the chronovisor folder, not in archive_handeler. It was fortunately not a difficult fix, but it makes the git history a bit of a mess.

After fixing the import, I added file_picker as a dependency, and added a basic button to use to create a file picker popup and linked the popup with the function to load the selected archive. This involved reading the file_picker docs; fortunately, the picker selection works on the web, as I am currently testing the app in a web environment.