Support SwiftPM warning control settings in generated Xcode projects

Tuist now decodes and maps SwiftPM’s modern target warning-control settings: treatAllWarnings, treatWarning, and enableWarning. They lower into the same Xcode build settings and flags SwiftPM itself uses, so the generated Xcode projects preserve the package author’s warning behavior. For Swift, treatAllWarnings/treatWarning map to OTHER_SWIFT_FLAGS (-warnings-as-errors/-no-warnings-as-errors and -Werror/-Wwarning). For C and C++, the same APIs map to OTHER_CFLAGS/OTHER_CPLUSPLUSFLAGS (-Werror/-Wno-error, -Werror=.../-Wno-error=..., and -W<name>). Packages such as Point-Free’s swift-dependencies 1.13.0, which uses newer SwiftPM warning-control APIs, now load through Tuist without failing during package decoding.