feat: paste from html

[LucasXu0]

• Use the 'html' package to parse the raw HTML string.
• Parse the result into a document structure.
• When pasting, replace the current selection with the new nodes.

For a single DOM element, we only need to insert it at the selected position.
For multiple DOM elements, we should split the selected node, merge it into the parsed nodes, and then insert the parsed nodes before removing the selected one.

[codecov]

Codecov Report

Merging #391 (fa1a625) into main (e5a10c4) will decrease coverage by 0.21%.
The diff coverage is 23.46%.

@@            Coverage Diff             @@
##             main     #391      +/-   ##
==========================================
- Coverage   76.09%   75.89%   -0.21%     
==========================================
  Files         252      252              
  Lines       10190    10274      +84     
==========================================
+ Hits         7754     7797      +43     
- Misses       2436     2477      +41     

Files Changed	Coverage Δ
...tor_component/service/keyboard_service_widget.dart	89.07% <ø> (ø)
...ortcuts/command_shortcut_events/paste_command.dart	28.31% <0.00%> (-51.69%)	⬇️
lib/src/plugins/html/html_document_decoder.dart	90.53% <94.73%> (+12.40%)	⬆️
lib/src/editor/util/color_util.dart	100.00% <100.00%> (+61.90%)	⬆️