Whiteboard: make "Undo/Redo" work well

Description

Problem

Undo action often doesn't revert to the original state. Sometimes it works, but other times it seems to skip an action in the history. For example, when adding a label to an arrow. If you add multiple objects to a section, undo steps back one object at a time.

Solution

To undo something the user has done, press Ctrl + Z (Windows) or Cmd + Z (Mac) until reaching the desired state. To redo an action, press Ctrl + Shift + Z (Windows) or Cmd + Shift + Z (Mac).

Note: the user can only undo or redo their own actions, not those made by other users.

Update the undo action behavior for different cases:

Text

The actions for border style, fill style, font style, size, font type, positioning, link and color must be reversible via undo.
The actions resize, duplicate, rotate, and remove from board must be reversible via undo/redo.

Shapes

The action changing shape must be reversible via undo
The actions for font style, size, font type, positioning, link and color must be reversible via undo.
The actions resize, duplicate, rotate, lock and remove from board must be reversible via undo/redo.

Stickers

The action Hide/show Author must be reversible via undo
The actions for font style, size, font type, positioning, link and color must be reversible via undo.
The actions resize, duplicate, rotate, lock and remove from board must be reversible via undo/redo.

Connectors

If the user modifies the line through points, each step should be recorded in the undo history

The actions for change line shape, change arrowhead, line style, add text and positioning must be reversible via undo.

Sections

The action changing size (1:1, A4 etc) , border style, fill style must be reversible via undo
Rename , Hide , Lock/Unlock section must be reversible via undo/redo
The actions resize, positioning, duplicate, and remove from board must be reversible via undo/redo.

Images

Upload: when multiple files are uploaded, the undo action should revert all of them at once, not one by one
The actions resize, duplicate, rotate, and remove from board must be reversible via undo/redo.

Pencil

Each pencil stroke should be undone step by step with the undo action
Each changes to the line style (thickness and color) should be undone step by step with the undo/redo action

Adding Entity or Multi-entities

When adding entity cards one after another Insert a card, the undo option should remove the cards in reverse order.
When multiple Multi-entity insert cards are added to the whiteboard the undo action should remove the stack of cards step by step. For example: if the user adds 10 features and then 10 stories, undo should first remove the 10 stories, then the 10 features.
The same logic applies to nested collections: if the user enables a nested stories collection for a feature, and then a nested tasks collection for a story, undo should first remove the task collection, then the story collection.

Relations

Relationships between entities should also take undo steps into account. For actions like Unlink and Unlink all, we currently show a toast with an "Undo" button on purpose. We need to make sure the undo step also works via the undo shortcut.

Convert to Entity

If the user has converted any possible object into an entity, then undo should not convert the entity card back into an object and should not remove the card from the whiteboard.

Duplicate

When duplicating any element, undo should revert the action (remove the duplicate from the canvas)

Group objects

If the user grouped or ungrouped objects, the undo/redo action should revert to the previous state

Align objects

Each changes to the Align objects (Align, Distribute, Auto align) should be undone step by step with the undo/redo action

Sending an item backward or forward, Bringing items to the back or front

Undoing a bring to front, send to back, bring forward, or send backward action restores the affected item's previous z-order index within its layer

Remove from board

If the user removed from board any element (text, shape, card etc.) or or several elements at once from the board, the undo action should bring it back

Clean Board

When clearing the whiteboard, undo history is erased. It can be restored via Whiteboard activity

Additional things:

? Do we need undo/redo buttons in the toolbar panel? Alex Tsayun