Fix ‘redefinition of module’ errors for precompiled XCFrameworks with module maps

Targets depending on precompiled XCFrameworks that include a module map no longer fail to compile with ‘redefinition of module’. Tuist now skips adding the XCFramework slice headers to HEADER_SEARCH_PATHS when a module map is present, because Xcode already exposes them through ProcessXCFramework. Cached library products without module maps keep their header search paths.