fix(move_block): move multiple lines up/down

[SiriusXT]

Closes #2191

1. Solve moving multiple lines of plain text/headings while preserving the selection
2. Keep moved blocks in view
3. fix(move_block): Make the object movable – When moving near objects (e.g. tables or horizontal lines), the selection was lost and Ctrl+Up/Down fell back to cursor movement. Upgraded the shortcut‐listening approach and enabled moving of objects, block quotes, etc.
4. Move objects/tables/texts simultaneously

[eliandoran]

@SiriusXT , do you need any support for this PR?

[SiriusXT]

@SiriusXT , do you need any support for this PR?

@eliandoran Currently, the movement of basic blocks has been solved, but there is still no good method for moving elements like Mermaid.
At present, elements like Mermaid can only be moved individually and cannot be mixed with other elements.
If you can solve this, that would be great. Otherwise, we can leave it for future.

[eliandoran]

@SiriusXT , we can ignore the issue with moving widgets such as Mermaid, for now.

[eliandoran]

Looks and feels pretty good!