Expose the main entry point for the tools via the library lets us run the tools
from the Flutter package, which simplifies the setup for end developers because
they don't need to declare a dependency on sky_tools directly.
sky_viewer.mojo no longer needs a window manager embedding as of
sky_engine 0.0.27, so this updates the sky_tools run_mojo command so it works
again. This really should be expressed in the pubspec dependencies to avoid
broken combinations but that needs to happen on the sky side.
This command will produce an flx package. Currently, this command doesn't work
because we don't have the Flutter compiler downloaded from Google storage yet.
A future patch will make that happen.
This command uses package:test to run Dart tests with sky_shell. For this to
work, we need https://github.com/dart-lang/test/tree/hacky-loader-hook to land.
We're also not smart enough to find sky_shell ourselves yet. Instead, we take
the path as input using an environment variable. Eventually, we'll be able to
get the sky_shell executable from package:sky_engine, but we don't yet ship
that executable.
