New features added to editor by squire

[rezaei92]

Added features and improved editor displaying as described in PR #1744, without using Squire-RTE.
Thank you.

[the-djmaze]

Your changes are not RTL related.

• It contains SVG images (which have no color based on theme colors)
• undo/redo is disabled
• Different changes in SquireUI.less without explanation
• Theme NextcloudV25+/styles.css without explanation

Sorry, but i must decline this PR as well.

[rezaei92]

Thanks for your feedback. While I understand your concerns, these changes were made to improve the editor. I'll provide more details. If necessary, I'll create separate PRs or issues for each point.

1. We've used SVGs for the 'text alignment' newly added feature because unicode characters doesn't exist for that and use SVGs for ordered, and unordered lists to provide a clearer and more user-friendly interface. I'm working to fix the SVG color for dark mode too.

2. The undo/redo functionality was initially disabled and hadn't working for me. By commenting out a few lines of code, we successfully enabled these essential features.

3. The modifications in SquireUI.less were designed to streamline the editor's layout and enhance its overall aesthetics. Specifically, we adopted a flexbox-based approach for the toolbar buttons, replacing the previous scroll-based layout. Additionally, we ensured correct displaying of SVG icons and the button order for right-to-left (RTL) languages.

4. The adjustments made to NextcloudV25+/styles.css were aimed at preserving a consistent and user-friendly appearance across different themes by overriding certain default styles.

Do you have any ideas or suggestions for accepting this PR?