feat: support copying divider from HTML

[LucasXu0]

<hr> should be parsed as a divider when pasting HTML.

[codecov]

Codecov Report

Attention: Patch coverage is 73.68421% with 10 lines in your changes missing coverage. Please review.

Project coverage is 71.99%. Comparing base (d24a7fc) to head (e4648cc).

Files with missing lines	Patch %	Lines
.../service/shortcuts/command/open_links_command.dart	0.00%	2 Missing ⚠️
...tyle/mobile_text_span_decorator_for_attribute.dart	66.66%	2 Missing ⚠️
.../editor/find_replace_menu/find_replace_widget.dart	75.00%	2 Missing ⚠️
...mat_double_character/format_double_characters.dart	0.00%	1 Missing ⚠️
...rmat_single_character/format_single_character.dart	0.00%	1 Missing ⚠️
lib/src/render/selection/cursor.dart	0.00%	1 Missing ⚠️
lib/src/render/selection/mobile_basic_handle.dart	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1024   +/-   ##
=======================================
  Coverage   71.99%   71.99%           
=======================================
  Files         319      319           
  Lines       15360    15346   -14     
=======================================
- Hits        11059    11049   -10     
+ Misses       4301     4297    -4     

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