[DE Team][8.15][Serverless] Bulk-update a rule's custom highlighted fields

[nastasha-solomon]

Fixes #5090

ESS previews:

• Manage detection rules | Modify existing rules settings: Added bullet to the second item in step 2
• BulkEditAction object | Possible BulkEditAction object values: Added the following params for bulk-updating custom highlighted fields:
  • add_investigation_fields
  • delete_investigation_fields
  • set_investigation_fields
• Create a detection rule | Configure advanced rule settings: Minor revisions to the description
• View detection alert details | Investigation: Expanded on the Highlighted fields description

Serverless previews: (Same changes, minus API updates)

• Manage detection rules | Modify existing rules settings
• Create a detection rule | Configure advanced rule settings
• View detection alert details | Investigation

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[e40pud]

Looks great! We need to do couple small updates, happy to chaat about those.

[e40pud]

Looks great, thank you!

[joepeeples]

I left a few fairly optional comments, so I'll go ahead and approve in case you choose to go with things as-is. Probably the stickiest point is the question about default Security indices, the other comments just nits.

[nastasha-solomon]

Verified that changes are on prod server.