[Discover] Pin records to top of data grid

[shaunmcgough]

In the selected records menu, there should be a new option called, Pin selected records, which pins the selected records to the top of the data grid. There should also be an option to unpin selected records, and if you unselect a record, it should unpin automatically.

Use case:
Actor: User
Action: User selects records, user clicks the selected records text, user clicks 'Pin selected records', records are pinned to the top.
Action: User has pinned records, deselects a record, it becomes unpinned
Action: User has pinned records, clicks selected records text, user has not selected additional records, the 'Pin selected records' text is changed to 'Unpin all records' and clicking it unpins all records.

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[kertal]

How should the pinned records behave in terms of scrolling? do they scroll? are they sticky?

[kertal]

Closing this because it's not planned to be resolved in the foreseeable future. It will be tracked in our Icebox and will be re-opened if our priorities change. Feel free to re-open if you think it should be melted sooner.