[ML] [AIOps] Pattern analysis tab in Discover enhancements

[jgowdyelastic]

Meta issue for follow on tasks for the initial work to add a pattern analysis tab to Discover #178916

• Replace expanded rows with flyout similar to the existing document viewer in Discover. Suggested here.
• Refactor menu item wrappers which currently reuse an existing discover class for their styles Suggested here.
• Investigate validation which reports 0% contain 3 or more tokens when data appears to contain tokens.
• Fix mobile view as per this comment.
• Investigate the occasional delay when pressing the cancel button
• Add a restart button after cancel has been pressed.
• Fix minor layout issues as per this comment.

[elasticmachine]

Pinging @elastic/ml-ui (:ml)