[ML] [META] Log pattern analysis improvements

[jgowdyelastic]

Meta issue to track requested improvements to the Log Pattern Analysis page.

• [x] Validate field selected for analysis https://github.com/elastic/kibana/pull/162319
• [x] Store all page options in the URL for reloading after a page refresh
  • [x] Field selection https://github.com/elastic/kibana/pull/162319
  • [x] Date range
  • [x] Search bar settings
• [ ] Drag to select time range in main chart
• [ ] Consolidate aiops to Discover link generation
• [x] The Discover links should add any query / filter from the search bar to the query from the pattern being explored
• [ ] Refactor DatePickerWrapper to improve places where it is used as a hook dependency https://github.com/elastic/kibana/pull/139005#discussion_r970532226
• [ ] Sticky document count chart, so it remains visible when scrolling and hovering / selecting rows at the bottom of the table
• [x] Improve empty state UX - for example by including information on how to use the view
• [x] Improve 'No results' messaging, such as when the analysis is run over a time range when there are no docs.

[elasticmachine]

Pinging @elastic/ml-ui (:ml)