[dmt] collect mount files

[diyliv]

Summary

• Parse files section in mount-points.yaml: the mount-points container rule only collected dirs, ignoring files entries.
• Fix: added Files []string field to mountPointsFile struct and iterate over mpf.Files alongside mpf.Dirs in collectMountPointsDirs.
• Test: added TestMountPointsContainerRule_FilesDeclared covering files section.
• Affected files: pkg/linters/container/rules/mount_points.go, pkg/linters/container/rules/mount_points_test.go

Context

The mount-points rule requires every volumeMount.mountPath in Deployment/DaemonSet/StatefulSet to be declared in a mount-points.yaml. However, mount-points.yaml supports both dirs and files sections, but the linter only read dirs. This caused false positives for mount paths declared as files (e.g., /etc/app/config.yaml, /run/xtables.lock) — the linter warned they were "not declared" even though they were present in files.

Example

Before (false positive):

Container "main" mountPath "/run/xtables.lock" is not declared in any mount-points.yaml

Even though mount-points.yaml contains:

files:
  - /run/xtables.lock

After: no warning — file mount paths are recognized.