Explode / Expand YAML Anchors before parsing the workflow

[ChristopherHX]

All yaml.Node usages in the act codebase do not expect the type AliasNode, to keep being maintainable replace all aliases by the Anchor target and check for cycles.

Originally posted by @ChristopherHX in https://github.com/nektos/act/issues/5893#issuecomment-3313130250

[alexgwolff]

updates?

[panekj]

Blocked by #5944

[ChristopherHX]

Blocker removed, now act need to catch up with security updates that can take some weeks...