When multiple views share a WebContent process (e.g. parent and child
views created via window.open()), we need to notify ALL of them when
the process crashes, not just one.
Previously, each view would overwrite the single crash callback on
WebContentClient, so only the last view to initialize would be notified.
This adds WebContentClient::notify_all_views_of_crash() which iterates
over all registered views and notifies each one. Child views also now
propagate crashes to their parent, and can be disconnected between
tests to prevent stale crashes from affecting subsequent tests.
Clipboard handling largely has nothing to do with the individual web
views. Rather, we interact with the system clipboard at the application
level. So let's move these implementations to the Application.
We currently create a separate headless-browser application to serve two
purposes:
1. Allow headless browsing to take a screenshot of a page or print its
layout tree / internal text.
2. Run the LibWeb test framework.
This patch migrates (1) to the main Ladybird executable. The --headless
flag enables this mode. This matches the behavior of other browsers, and
means we have one less executable to ship at distribution time.
We want to avoid creating too many AppKit / Qt facilities in headless
mode. So this involves some shuffling of application init to ensure we
don't create them until after we've parsed the command line arguments.
Namely, we avoid creating the NSApp in AppKit and QCoreApplication in
Qt. Doing so also requires that we don't create the application event
loop until we've parsed the command line as well, because the loop we
create depends on whether we're creating those UI facilities.
