[SIEM][Detections Engine] - Add rule markdown to timeline global notes

[yctercero]

Summary

This is part of #59176 - broke up into smaller PRs.
Frontend PR - #60108
Backend PR - #59796

This PR adds functionality for rules investigation guide markdown field - referred to here as "rule note" (not to be confused with timeline notes). When opening a signal in timeline, if a "rule note" exists, it will create a new global timeline note with the guide content as the first note. Similar to how the other rule fields function, if "rule note" is updated, the new content will apply to new signals generated from that new rule version, timeline notes created from earlier rule versions are not updated with the new "rule note".

To test, ensure you have a rule activated that includes a note. Go to Detections -> Manage signal detection rule -> select the rule that includes note -> under Detected Signals, click on timeline icon (Investigate in timeline). You should see the timeline open (with either the specified timeline template or default timeline template) and see a Note count of 1 that includes the rule note content.

• Duplicating a timeline - the new timeline should not include any notes
• Creating a timeline
  - if a rule guide exists, you should see 1 note in the new timeline that includes the guide content
  - if a rule guide does not exist, you should see 0 notes in new timeline

(https://github.com/elastic/kibana/blob/master/CONTRIBUTING.md#cross-browser-compatibility)

Per design, updated hover text from 'View in timeline' to 'Investigate in timeline':

Per design, updated 'Investigation notes' to 'Investigation guide':

Checklist

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Unit or functional tests were updated or added to match the most common scenarios
• This was checked for keyboard-only and screenreader accessibility
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser
• This was checked for cross-browser compatibility, [including a check against IE11]

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[FrankHassanabad]

LGTM

[yctercero]

@elasticmachine merge upstream

[yctercero]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: d7c3955

History

• 💚 Build #36956 succeeded 2982793
• 💔 Build #36932 failed 444b915
• 💚 Build #36731 succeeded f1d635f
• 💔 Build #36702 failed 23563b8
• 💚 Build #36398 succeeded b56731b

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)