Refactor sorter

[mohamedsalem401]

For #6122 and possibly #4323 (as we will significantly reduce calls to the DOM).

Changes

• Split the sorter into multiple classes.
• Change how we calculate drop position.
• Fix the issue with the StyleManager.

Pre-Merge Checklist:

• Canvas
• Style manager
• Layers
• Blocks
• Sorter event triggering: Is the sorter triggering events as expected (e.g., sorter:drag:start)?
• Dropping image into the canvas
• D&D multiple components
• Rollback button
• Textable component D&D

[mohamedsalem401]

@artf

• What do you think about the tests for the old sorter? Should I update them?
• There's a sorter in the blocks view, but it doesn't seem to be used anywhere that I know of. https://github.com/GrapesJS/grapesjs/blob/dev/packages/core/src/block_manager/view/BlocksView.ts