This is the last Gradle project that isn't in the srcdir. Since base/
doesn't have the correct package prefix directory structure, we still
need to symlink, but we only need one link. This effectively
deprecates |mach gradle-install|.
This should improve the robustness of our Gradle configuration,
ensuring that we always have projects to import. Since
settings.gradle executes very early in the IDE import project
sequence: before Gradle project evaluation time, and thus before any
Gradle task is executed, we should always see a complete project. (It
was possible to see incomplete Gradle configurations if |mach
gradle-install| hadn't been run at just the right time.)
IntelliJ's exclusion mechanism (for Gradle-based projects) is not very
flexible; we get just idea.module.excludeDirs. This patch crawls the
file system to skip what we can.
The sub-project definitions are still in the object directory (and
still installed by |mach gradle-install); over time, we'll migrate
them out.
The Gradle wrapper and {settings,build}.gradle in topsrcdir are
identical to those in mobile/android/gradle. I don't like the
duplication, but I also don't want the burden of keeping the two
configurations identical. We'll move away from the configuration
using mobile/android/gradle as quickly as we can.
