Stop package base settings from clobbering SwiftPM target bundle identifiers

Fixes a regression where Tuist copied a package-wide PRODUCT_BUNDLE_IDENTIFIER template onto each generated SwiftPM target, producing invalid bundle identifiers for underscore-prefixed modules and breaking build-for-testing. With the fix, PRODUCT_BUNDLE_IDENTIFIER is excluded from the base settings propagated to SwiftPM targets, so each target keeps its sanitized bundle identifier while other base settings such as EXCLUDED_ARCHS still flow through. Projects that use a package-wide PRODUCT_BUNDLE_IDENTIFIER and depend on packages like swift-collections or swift-numerics can build for testing again.