Dependency Mock Outputs Missing Bucket

Dependency mock_outputs apply when the state bucket doesn't exist yet

When reading a dependency's outputs directly from remote state (--dependency-fetch-output-from-state), Terragrunt fell back to mock_outputs only when the state object was missing, not when the S3 bucket itself didn't exist. A dependency on an environment that hadn't been bootstrapped yet would fail instead of using its mocks.

A missing bucket is now treated the same as a missing state object, so commands like plan and validate can resolve mocks before the dependency's backend has been created.