* Allow ILM move-to-step without `action` or `name`
This commit enhances ILM's move-to-step API to allow dropping the `name`, or dropping both the
`action` and `name`. For example:
```json
POST /_ilm/move/foo-1
{
"current_step": {
"phase": "hot",
"action": "rollover",
"name": "check-rollover-ready"
},
"next_step": {
"phase": "warm",
"action": "forcemerge"
}
}
```
Will move to the first step in the `forcemerge` action in the `warm` phase (without having to know
the specific step name).
Another example:
```json
POST /_ilm/move/foo-1
{
"current_step": {
"phase": "hot",
"action": "rollover",
"name": "check-rollover-ready"
},
"next_step": {
"phase": "warm"
}
}
```
Will move to the first step in the `warm` phase (without having to know the specific action name).
Bear in mind that the execution order is still entirely an implementation detail, so "first" in the
above sentences means the first step that ILM would execute.
Resolves#58128
* Apply Andrei's wording change (thanks!)
Co-authored-by: Andrei Dan <andrei.dan@elastic.co>
* Log index and policy name when the concrete step key can't be resolved
Co-authored-by: Andrei Dan <andrei.dan@elastic.co>
3d5843a236