Re-enable `key in somenode` construct after YAML new world order

Daniel Silverstonerequested to merge
danielsilverstone-ct/reenable-key-in-node into master

Description

As discussed in #984 (closed) the limitation on key in somenode is no longer valuable and instead the construct should be reenabled. This MR does that, and reverts the relevant parts of the YAML new-world-order which used Plugin.node_has_member() or _yaml.node_contains() as appropriate.

Changes proposed in this merge request:

  • Permit key in somenode
  • Remove Plugin.node_has_member()
  • Remove _yaml.node_contains()

Merge request reports