* Add initial header drag preview implementation

* Add drag column preview

* Rename inner preview widgets

* REname dropHeaderAtPosition

* Add lines preview

* Change mouse curson when hover a selected header

* Reorder preview clean up

* Fix preview using the latest selection

* Render drag preview independet of selections

* Fix selection tap initiating header drag

* Set header index as a range

* Add is header selected method to selection controller

* Move action dispatch to methods

* Fix preview with frozen panes

* Set drop action to move the selection around

* Add header cancel drag intent

* Move dragging property to its own state class

* Rename reorder preview to header drag and drop

* Blocks a drop action within the header range

* Add header drag state test

* Move header drag and drop actions to its own files

* Add intent docs

* Add drag n drop preview theme

* Add docs

* Fix format

* Add a configuration to swayze scope

* Fix test

* Fix const warning

* Fix typos

* Fix some selections no being dragged properly

* Add a brief doc on why we use basic cursor for drag

* Fix header drag and drop with frozen panes

* Move drag state to its own class

* Add end boundary drop test

* Add header gesture detector tests

* Fix dragging overlaping selections

* Set a single action mock

* Typo

* Move drag and drop style to its own class

* Fix comment