REVIEW-2568: Minor fix
Moved C and ASM language support into separate packages
Renames in C++ land
- BinariesPlugin -> NativeBinariesPlugin
- BinaryOutputTask -> BuildBinaryTask
Reorganised plugins for C++

- Renamed NativeBinariesPlugin -> NativeBinariesModelPlugin
- Added NativeBinariesPlugin that creates general tasks for native binaries
   - Link task, Static library task, Install task
- Extracted CppLangPlugin, CLangPlugin and AssemblerLangPlugin out of CppPlugin
   - These plugins provide language support (including tasks) but no project conventions
- CppPlugin now applies all language support and provides project conventions
Fix toString representations of native source sets