feat: enable drag-and-drop functionality for text in the editor

[Jayaprakash-dev]

I made this PR after coming across the issue Drag & drop content #3980. It restricts dragging and dropping block components, allowing only the movement of plain text.

This feature allows users to select text and drag it to a preferred location within the editor. The implementation ensures that only the plain text of the selection is copied, without including the node delta or any of node data associated
with the selected text. Instead, it 'adapts to the node' it is going to be placed in.

appflowy.drag.and.drop.text.feat.demo_comp.mov

[codecov]

Codecov Report

Attention: Patch coverage is 46.86567% with 178 lines in your changes missing coverage. Please review.

Project coverage is 75.70%. Comparing base (3cd5602) to head (cde0f60).
Report is 254 commits behind head on main.

Files with missing lines	Patch %	Lines
...t/service/selection/desktop_selection_service.dart	25.38%	97 Missing ⚠️
...ib/src/render/selection/dashed_cursor_painter.dart	0.00%	21 Missing ⚠️
lib/src/editor_state.dart	77.77%	8 Missing ⚠️
...block_component/bulleted_list_block_component.dart	61.11%	7 Missing ⚠️
...ading_block_component/heading_block_component.dart	61.11%	7 Missing ⚠️
...block_component/numbered_list_block_component.dart	61.11%	7 Missing ⚠️
...aph_block_component/paragraph_block_component.dart	50.00%	7 Missing ⚠️
...t/quote_block_component/quote_block_component.dart	61.11%	7 Missing ⚠️
...ist_block_component/todo_list_block_component.dart	61.11%	7 Missing ⚠️
...base_component/selection/block_selection_area.dart	71.42%	6 Missing ⚠️
... and 3 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #685      +/-   ##
==========================================
- Coverage   76.46%   75.70%   -0.76%     
==========================================
  Files         295      296       +1     
  Lines       13094    13419     +325     
==========================================
+ Hits        10012    10159     +147     
- Misses       3082     3260     +178     

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