Path traversal in Fleet Helm valuesFiles allows disclosure of files outside the bundle directory

A user who can supply bundle content to a repository referenced by a GitRepo resource, for example through Git push access, or through permission to create or modify a GitRepo, can cause SUSE Rancher Fleet to read files from the filesystem of the environment that processes the bundle and include their contents in the generated Bundle resource. This can expose configuration or credential material that the user has no Kubernetes RBAC permission to read, including Helm registry credentials made available to the bundle-processing job when per-path Helm credentials are configured. This affects Fleet 0.16 before 0.16.2, 0.15 before 0.15.7, 0.14 before 0.14.11, 0.13 before 0.13.16, 0.12 before 0.12.20 and potentially older unsupported versions.