Fix layer management issues

[naschmitz]

There were some issues Qiusheng and I noticed while testing:

• Toggle all visibility on/off didn't update layer checkboxes
• Removing a layer didn't reflect in the layer manager
• Swapping/shuffling layers didn't reflect in the layer manager

These should all be fixed now.

[github-actions]

🚀 Deployed on https://651505dd8a920c4d00788958--opengeos.netlify.app

[giswqs]

Thank you for fixing it so quickly. I wondered if the basemap should also be turned off when the All layers off is checked. One use case would be when the data layer only covers a small part of the part and the user only wants to show the data layer without the basemap in the background. With the current setting, the basemap is always shown. Although it can be turned of setting m.layers[0].visible=False, maybe the toggle button should support this as well.

[giswqs]

I pushed a commit that allows the basemap layer to be toggled off. We can revert it if there a strong opinion again this.