Closes #9694

Fixes #9170

Fixes #9686

Fixes #9637

Fixes #9596

This also fixes/improves AbstractDateField validation.

Resolves #9372

This patch changes Grid Columns, so they can have different value and presentation types. A presentation provider can be given when setting the renderer for a column. This provider takes the value of the column on a row and chooses what to present for this value. Using this approach it is easier to have an editor for the actual backing data instead of the presentation of it.

Fixes #8656
Resolves #9588

* Enable row height setting for Tree
* Add content mode for captions
* Align expander element by default to top

The content mode allows use of preformatted and
HTML captions that bring value to row height

Fixes #9411

Fixes #8316

Fixes #9449
Fixes #9490
Fixes #9448
Fixes #9465

Addresses #9465

Fixes #9488

Fixes #9483

Fixes #9079

Fixes #8548

Fixes #9419

When CSS transform has been applied, the drag image is missing (safari),
or gets offset (FF). Fixed by using custom drag image without transform,
and checking for transforms on parent DOM tree. Does NOT fix #9408
When there are frozen columns used, the image needs should not look weird because of the frozen column transitions.
The multiselection column is now not shown it is frozen.

Fixes #9261

Fixes #9403

Also makes sure that the drop location and target row return something sensible in drop event.
Clarifies docs on drop location.

* Make it possible for grid drop target to accept dragged data when grid is empty (#9068)
* Make return type of getDropTargetRow() optional

Immediately clean connectors which the client side does not know about

Fixes #9303

* Add ability to set multiple drag data generators for any drag data type
and change default to be accepted by spreadsheet applications such as Excel

* Refactor common methods of InMemoryHierarchicalDataProvider and ListDataProvider to a single interface
* Rename HierarchyData and InMemoryHierarchicalDataProvider, introduce HasHierarchicalDataProvider
* Additionally adds a helper method for recursive constructing
TreeData with a child item provider.

* Add ItemClick event to Tree
* Add collapse provider and style generator to Tree

Fixes #9121

* Refactor Html5 DnD client side based on API review

- Moved classes to "correct" packages.
- Removed method DragSourceExtension.clearDataTransferText()
- Remove ButtonDragSource in favor of more generic API

First step of mobile DND support.

- Add mobile html5 dnd support using polyfill
- Adds a switch for enabling mobile html5 dnd support
- Adds polyfill only when needed
- Ignore native Android Chrome drag start because doesn't work properly
(no dragend event fired)
- Add documentation on enabling mobile HTML5 DnD support
- Add mention of drag-drop-polyfill license
- Fixed issue in polyfill when not using "snapback"
- Add mention of forked polyfill

Fixes #9174

Fixes the remaining issue from #3944 for Firefox so that a click on the checkbox label calls the focus listener.

Fixes #9290

Reset HDC when encountering unexpected changes in the data.

Additionally this patch fixes an issue with client and server caches
getting out of sync during resets.

Doesn't fix #9261, drag image missing on Safari when dragging grid row because
that has position: absolute and offset.

Fixes #9241

- Always set some drag data
- Set the dropEffect on dragEnter and dragOver events on drop target
- Send the dropEffect to server on drop event with disclaimer of current support
- Remove _dragOverCriteria_ and use _dropCriteria_ for `dragenter`, `dragover` and `drop` criteria

Tested manually basic DnD and Grid DnD on Mac with Chrome, Firefox, Safari.
Safari is still missing drag image (regression).

Tested manually basic DnD and Grid Dnd on Windows IE11 and Edge.
Drop event for both is still not working properly #9174.

This patch introduces a Tree component, implemented as a Composite
using TreeGrid. As initial version of the component, some functionality
of the old Tree component has been left out for now.

Partly addresses #8617

* Fix race condition between rendering Grid and setting up headers
* Remove Grid default headers when initializing the widget
* Fix header clean up, add null check to select all checkbox

Refactors AbstractGridKeyEvent, AbstractGridMouseEvent and their
descendants to follow the pattern used in other GWT DomEvents.

Fixes #7633

A composite is included in the server side hierarchy and in the connector
hierarchy on the client side but does not have its own widget or DOM.

To ensure that captions etc are renderer correctly for the root contents,
the client side connector returns both the widget and state for the content
connector.

Server side API related to width and height are automatically forwarded to
the root component to enable easy use of the composite inside different
layout configurations.

Other server side API inherited from AbstractComponent is unwanted, should be
optional and therefore throw an exception by default.

Resolves #2458

Fixes #1149

Fixes #8901