Add support for force merge action to ILM policy form's hot phase

[cjcenizal]

Per the force merge docs page, force merge is available in both the hot and warm phases. Our UI needs to be updated to support this action.

Note the following conditions:

To use the forcemerge action in the hot phase, the rollover action must be present. If no rollover action is configured, ILM will reject the policy.

We need to add logic to hide the forcemerge action if rollover isn't enabled.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[cjcenizal]

Related to elastic/elasticsearch#61666

[yuliacech]

Closed via #77193.
Duplicate of #57642.