Add 2 new features

[blotterchains]

Actions before raising this issue

• I searched the existing issues and did not find anything similar.
• I read/searched the docs

Is your feature request related to a problem? Please describe.

i wanted to implement merging and spliting objects in one frame
related to this link
#5006
and make some changes to cvat-canvas to add split

Describe the solution you'd like

i've done snapping feature for polylines that cvat not supported yet within cvat-canvas(autoboarder)
and add a function and a new object to function and do some math.

i read the cvat codes and know good how to change logics
but now i want to add merging and split feature for shapes and making it in one shape or two shape related to other issues and have some problem with changing react.js state when i click on my new button.
i changed the state from cvat-ui and active the button on ui but the cursor not change to select mode(like merge mode)

i changed many places in cvat-canvas like
canvasModels.ts
canvasController.ts
canvasView.ts
add a file
and named it
mergeoverhandler.ts

and in cvat-ui

annotation-actions.ts
control-side.tsx
control-side-bar.tsx
and add

merge-overlay-control.tsx

please tell me how to add new tools same as merge(but my own logic)
the problem is i changed every things and every things is good when the states come to canvas-wrapper and call my own function(mergeOver(enabled:true)) the cvat-canvas not allow me to change state to select cursor(for selecting objects)

and tell me how to debug and send you some data to better understanding

Describe alternatives you've considered

No response

Additional context

No response