It is currently a bit messy to pass these options along from main() to
where WebContent is actually launched. If a new flag were to be added,
there are a couple dozen files that need to be updated to pass that flag
along. With this change, the flag can just be added to the struct, set
in main(), and handled in launch_web_content_process().
We can easily add hooks to notify the browsers of these events if any
implementation-specific handling is needed in the future, but for now,
these only repaint the client, which we can do in ViewImplementation.
Storing the backup bitmap is the same across Browser and Ladybird. Just
peform that work in LibWebView, and handle only the implementation-
specific nuances within the browsers.
This also sets the default callback to do what every non-Serenity
browser is doing, rather than copy-pasting this callback into every
implementation. The callback is still available for any platform which
might want to override the default behavior. For example, OOPWV now
overrides this callback to use FileSystemAccessClient.
This will help a lot with developing chromes for different UI frameworks
where we can see which helper classes and processes are really using Qt
vs just using it to get at helper data.
As a bonus, remove Qt dependency from WebDriver.
