fix: insert the pasted nodes after current selection if they start with a non-delta node

[LucasXu0]

closes AppFlowy-IO/AppFlowy#6440

If the pasted content starts with a non-delta block, insert the content below the current selection. Otherwise, keep the original logic.

[codecov]

Codecov Report

Attention: Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.

Project coverage is 72.04%. Comparing base (c5de9ed) to head (7bdbf94).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ervice/shortcuts/command/copy_paste_extension.dart	81.81%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #908      +/-   ##
==========================================
+ Coverage   71.89%   72.04%   +0.15%     
==========================================
  Files         318      318              
  Lines       14955    14962       +7     
==========================================
+ Hits        10752    10780      +28     
+ Misses       4203     4182      -21     

Flag	Coverage Δ
	72.04% <81.81%> (+0.15%)	⬆️

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