Fix Xcode cache daemon to use the private TUIST_CACHE_ENDPOINT override

When Tuist dispatches builds to runners using a private cache endpoint via the TUIST_CACHE_ENDPOINT override, the Xcode compilation cache (CAS) daemon now uses that same endpoint instead of falling back to the public one. Previously, the module cache honored the override, but the CAS daemon, which runs as a launchd agent and does not inherit the caller’s environment, kept resolving the public endpoint, making the Xcode cache net-negative on full compiles. Forwarding TUIST_CACHE_ENDPOINT into the daemon’s environment ensures the cache traffic is routed consistently and improves compile times for CI builds using a private cache.