Snapshot management UI

[bowenlan-amzn]

Description

[Describe what this change achieves]

Issues Resolved

opensearch-project/index-management#280

Check List

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[AWSHurneyt]

Minor note. This element seems to be converting a preset time option to a cron expression as expected, but doesn't convert the other way around.

For example, 30 4 * * * should be Daily at 4:30 AM. However, if you select the Daily at 2:00 AM preset option, change the Schedule frequency to Custom (Cron expression), paste 30 4 * * *, and then change the Schedule frequency type back to Daily, the 2:00 AM option will still be selected. I wouldn't think this is a blocker, but just wanted to call that out in case you intend to support that conversion direction.

[AWSHurneyt]

When editing an existing policy, only the Policy name and Description fields seem to pull the existing definitions for editing; the rest of the form has the default values.