The main motivator here was noticing that --disable-sql-database did not
work with AppKit. Rather than re-implementing this there, move ownership
of these classes to WebView::Application, so that each UI does not need
to individually worry about it.
If the Downloads directory exists, we will use it (note that this will
respect the XDG_DOWNLOAD_DIR environment variable).
Otherwise, we will ask the UI layer to retrieve a download directory
from the user. This directory is not saved, so it will be re-prompted
every time. Once a proper settings UI is complete, we will of course
integrate with that for persistent settings.
This creates a TimeZoneWatcher in the UI process to inform all open
WebContent processes when the time zone changes. The WebContent process
will clear its time zone cache to retrieve a fresh zone the next time
it is asked for one.
When using a configuration without a swift compiler, we need to no-op
the swift annotations. Other, cleverer solutions beyond the has include
all fell flat in the face of the clang modules implementation used by
swift to parse-once use-everywhere each module.
Currently, if we want to add a new e.g. WebContent command line option,
we have to add it to all of Qt, AppKit, and headless-browser. (Or worse,
we only add it to one of these, and we have feature disparity).
To prevent this, this moves command line flags to WebView::Application.
The flags are assigned to ChromeOptions and WebContentOptions structs.
Each chrome can still add its platform-specific options; for example,
the Qt chrome has a flag to enable Qt networking.
There should be no behavior change here, other than that AppKit will now
support command line flags that were previously only supported by Qt.
This large commit also refactors LibWebView's process handling to use
a top-level Application class that uses a new WebView::Process class to
encapsulate the IPC-centric nature of each helper process.
