* Moves the imports of winreg and Tk, into the functions that use them,
with winreg behind a guard clause. This should hopefully mean that if
you're not on Window or not using `ui=app` we won't trip over either
of these due to them not being there.
* On windows insist on the presence of webview2 as the embeddable
browser for `ui=app`. If we can't find it, effectively switch back to
`ui=web`. This should prevent pywebview trying to use MSHTML, whilst
saying its deprecated, and apparently we are too much for poor old IE11
* Add webview2 runtime droppings to .gitignore.
* If we can't bind to args.server_port get another suitable port from
the OS and advise the user that we did this in the UI.
* Make `ui=web` mode use 'SHARK AI Studio' as its title. This makes it
consistent with `ui=app`.
* Replace the generic gradio favicon with a nod swirl one instead.
