ui: upgrade from bootstrap 4 to bootstrap 5

[dmsimard]

What is the idea ?

One of the vendored static asset for the reporting UI is bootstrap via bootswatch themes: https://github.com/ansible-community/ara/tree/master/ara/ui/static

Unfortunately, bootstrap 5 was still in beta (or alpha?) when the last UI refresh was done and so I picked bootstrap 4 to do it at the time.

bootstrap 5 as well as the bootswatch themes are available now, providing an opportunity to update them.

bootstrap 5 says it doesn't need jquery anymore but I'm not 100% sure we don't use it elsewhere. If it turns out we don't need it we can remove it.

[dmsimard]

I've created a PR to see what it looks like: https://github.com/ansible-community/ara/pull/340