feat: support moving a block to become a child of another block

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 38.09524% with 13 lines in your changes missing coverage. Please review.

Project coverage is 72.38%. Comparing base (0a0154f) to head (9432992).

Files with missing lines	Patch %	Lines
...t/service/selection/desktop_selection_service.dart	0.00%	11 Missing :warning:
...or/editor_component/service/selection_service.dart	0.00%	1 Missing :warning:
...or_component/service/selection_service_widget.dart	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #895 +/- ## ========================================== - Coverage 72.41% 72.38% -0.03% ========================================== Files 317 317 Lines 14797 14794 -3 ========================================== - Hits 10715 10709 -6 - Misses 4082 4085 +3 ```

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