This allows Ladybird to be the default browser on macOS, and allows for
opening some file types (.html, .svg, .md, etc.) with Ladybird.
Note this currently only works in the GN build (and thus the Qt chrome).
The CMake build does not set up the Resources directory properly for
macOS to run the Ladybird app without $SERENITY_SOURCE_DIR set.
We had a mismatch in the GUI Identifier property, causing warnings in
Xcode. It was also missing the Product Identifier Xcode property on
ladybird itself, causing another warning.
Copy all our helper processes to the ladybird.app bundle directory so
that they can be found by ``open ladybird.app`` and the Xcode debugger.
For the future, we should look in ../Resources for resources on macOS.
Copying resources to that directory requires more CMake-fu.
