When a window containing a WebView becomes visibile, we have to inform
WebContent. This was only implemented for the Tab class (not Inspector
or Task Manaager).
This patch adds LadybirdWebViewWindow to contain the bare minimum needed
to render a LadybirdWebView. All windows containing a WebView inherit
from this class, to ensure their WebContent processes know they became
visible.
The AppKit Application class is responsible for launching all helper
processes. This had to be moved to a .cpp file because we were unable to
include headers with the Protocol namespace in .mm files, as they would
conflict with the Protocol interface defined by Apple.
Now that this namespace has been renamed to Requests, we can remove this
workaround.
