This mode allows us to test the HTTP disk cache with two mechanisms:
1. If RequestServer is launched with --http-disk-cache-mode=testing, it
will cache requests with a X-Ladybird-Enable-Disk-Cache header.
2. In test mode, RS will include a X-Ladybird-Disk-Cache-Status response
header indicating how the response was handled by the cache. There is
no standard way for a web request to know what happened with respect
to the disk cache, so this fills that hole for testing.
This mode is not exposed to users.
This is used by tests to set the default time zone to UTC.
This is because certain tests create JavaScript Date objects, which are
in the current timezone.
We only supported headless clipboard management in test-web. So when WPT
tests the clipboard APIs, we would blindly try to access the Qt app,
which does not exist.
Note that the AppKit UI has no such restriction, as the NSPasteboard is
accessible even without a GUI.
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 have a test for localStorage that repeatedly adds new items until the
quota is exceeded:
`webstorage/storage_local_setitem_quotaexceedederr.window.html`.
This test becomes significantly slower when localStorage is backed by
SQL database. Let's disable database usage in test mode for now, as this
test is likely to be flaky on CI due to timeouts.
You would have to just know that you need to define the constructor with
this declaration. Let's allow subclasses to define constructors as they
see fit.
This is causing errors on the WPT runner, which does not have a display
output. To do this requires shuffling around the Main::Arguments struct,
as we now need access to it from overridden WebView::Application methods
after construction.
Now that headless mode is built into the main Ladybird executable, the
headless-browser's only purpose is to run tests. So let's move it to the
testing directory and rename it to test-web (a la test-js / test-wasm).
