Introducing the new C++ plugins

Gradle introduces new C++ plugins (cpp-application, cpp-library, cpp-unit-test) that replace the older software model plugins. The plugins support building C++ libraries and applications on macOS, Linux, and Windows with GCC, Clang, and Visual C++. Key features include Gradle's dependency management for C++ (including Maven repository support), Xcode IDE integration, Google Test unit testing, build caching for faster incremental builds, variant-aware debug/release builds, Maven/Ivy publishing, and composite builds. The plugins are still a work in progress with some limitations around binary publishing and OS/architecture awareness.