Add feat: make winamp's window order configurable; Prevent windows from moving arbitrarily

[curiousRay]

Description of the Change

Closes #10 (https://github.com/10up/retro-winamp-block/issues/10#issuecomment-1982053604) Closes #83

Added configuration items for winamp block to set the windows' displaying order.

The Wordpress blocks can be placed into post/page, as well as sidebar widget. I've set rules separately. If you have any suggestions about these rules, just feel free to leave comments.

• Main window is forcedly displayed.
• All windows are NOT able to be dragged arbitrarily.
• The windows are displayed by the order of configuration only for general viewing mode (not for post/page editing mode)

winamp block in post/page

winamp block in sidebar widget

How to test the Change

1. Install the plugin
2. Add a winamp block in post/page/sidebar widget
3. Load media file so that the player can display
   • The winamp's windows cannot be dragged arbitrarily
4. In block setting tab, configure EQUALIZER/PLAYLIST/MILKDROP 's position as you wish
   • The position's change won't happen right now in editor mode
5. Click "Publish"/"Update" to save the post/page, or save the sidebar widget
6. Preview the post/page, the winamp windows should align according to the configuration.

[!NOTE]
Known issue before this PR: If two or more blocks appear in the same webpage, only one winamp instance will be created.

Changelog Entry

Added - New feature: added configuration items for winamp block to set the windows' displaying order. Fixed - Bug fix: added javascript code to prevent winamp windows from unwanted moving.

Credits

Props @dejalavidavolar

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests pass.