Simplify the geemap module

[giswqs]

This PR simplifies the Map class geemap module, making the widgets modular so that each widget can be added/removed programmatically

[github-actions]

🚀 Deployed on https://64757490cecdad17e0d48be6--opengeos.netlify.app

[giswqs]

@jdbcode The inspector GUI has been separated from the Map.__init__() method. It can now be activated as follows:

Map.add_inspector()

[giswqs]

The Layer Manager GUI has been separated from the Map.__init__() method. It can now be activated as follows:

Map.add_layer_manager()

[giswqs]

After separating the Inspector GUI and Layer Manager GUI from Map class, the number of lines of source code for the Map.__init__() method has been reduced from 1377 lines to 695 lines, almost 50% reduction. The widgets are now much easier to manage.

[jdbcode]

This is great! The simplification of the Map class is awesome!