Add airGappedChecksum field to check workload version before rollout

[Danil-Grigorev]

What this PR does / why we need it: This change adds AirGappedChecksum field to agent config. By using this field, a user might declare expected sha256sum checksum for the air gapped manifests and prevent incomplete or different package installation on the host.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #297 Depends on #313 for fuzzy test changes to make CI green

Special notes for your reviewer:

Internals of the curl -sfL https://get.rke2.io in the air-gapped mode already verify the contents of provided tar files based on the checksum from sha256sum-<arch>.txt. Therefore the AirGappedChecksum declares the expected checksum for this file only to connect API definition with the prepared host pre-bootstrap state.

Checklist:

• [ ] squashed commits into logical changes
• [ ] includes documentation
• [x] adds unit tests
• [ ] adds or updates e2e tests

[salasberryfin]

LGTM pending fixing CI checks and resolving @alexander-demicev's comment.