Fix deadlock when generating or installing projects with SPM dependencies

tuist generate and tuist install could hang indefinitely on projects that include Swift Package Manager dependencies. The CLI was holding SwiftPM’s scratch-directory lock while spawning swift package dump-package for the root manifest, so the child process blocked trying to acquire the same lock. This release narrows the lock scope to the direct file reads that need it, then releases the lock before invoking any swift package subprocesses. Projects with SPM dependencies now generate and install without freezing.