Add Convert-Index-To-Remote Action for issue #808

[wntmddus]

Description

Currently Searchable snapshot features are available from Opensearch 2.6 version. But this feature itself would not make the fully automated searchable snapshot possible without convert_index_to_remote action within ism actions. Currently ISM plugin does not provide any form of restore action as part of ism actions.
Solution.
Adding convert_index_to_remote action that performs remote restore on snapshot that was created in previous action or stages and that into search nodes as REMOTE_SNAPSHOT. Only thing that need to be passed in is repository name where customer need to assign their repository first then use that to take snapshot and restore.
"convert_index_to_remote": { "properties": { "repository": { "type": "keyword" } } },
Since actions in policy are initially going through schema validation through schema in opendistro-ism-config.json file, this need to be added in here so that we can submit policy with new action.
Then Added new AttemptRestoreStep and WaitForRestoreStep to perform restore.
Then Single ConvertIndexToRemoteAction will perform AttemptRestoreStep and WaitForRestoreStep to perform restore.
Adding this functionality to the user would benefit them to have fully automated searchable snapshot feature on all of their clusters.

Documentation PR: opensearch-project/documentation-website#8638

Related Issues

Related Issue #808

Check List

• [V] New functionality includes testing.
• [V] New functionality has been documented.
• [v] API changes companion pull request created. not required
• [V] Commits are signed per the DCO using --signoff.
• [V] Public documentation issue/PR created.

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