* [function] Support to remove header sequence when disable it
spec:
In edit mode:
- when click icon to enable auto sequence, add sequence immediately
- when click icon to disable auto sequence, remove already added sequence
In preview/read mode:
- auto sequence icon should be unchecked and disabled
For readonly file, always disable the auto sequence icon.
* [bugfix] Do not let auto sequence ruin the undo history
All the header sequence auto-update should be treated as one edit action.
So that user can undo auto-update by pressing undo twice.
(One undo for the auto-update change, and one for the original header change)
* Refactor and reformat according to PR feedback
1. De-duplicate the images occur multiple times in the note;
2. Refresh the read mode and edit mode preview after the directory path
change;
3. Update init images and inserted images after the directory path
change;
