Ability to reorder columns in table view

Requirements

1. User can reorder columns within the table
   1. Supported by drag-and-drop and keyboard shortcut when column header is focused. Note: In a future feature we will also offer this in a column actions menu.
   2. User changes are saved/persistent. This would be user-specific, and stored for the namespace (in the future it would be part of the specific Saved View)