SwiftPM warning control settings propagate to generated Xcode projects

Tuist now understands the SwiftPM target build settings treatAllWarnings, treatWarning, and enableWarning (used by packages like swift-dependencies 1.13.0) and lowers them into OTHER_SWIFT_FLAGS, OTHER_CFLAGS, and OTHER_CPLUSPLUSFLAGS the same way SwiftPM does. Package decoding no longer fails on these settings, and the generated Xcode project preserves the package author’s warning behavior. Unsupported combinations (linker warning controls, Swift enableWarning) are reported explicitly.