Style Editor improvements

[allyoucanmap]

• Align Apply / Copy from buttons with the Code editor selection, both for Maps and Datasets
• Harmonize the positioning of the Copy from panel for Maps and Datasets.
• Remove the spinner from the Apply button and make the Apply button only appear when the style is changed
• Add some spacing between Apply and Copy from buttons
• Adopt MD5 hash of the style body for a consistent management of visual / code style editor geosolutions-it/MapStore2#7671
• Remove the zoom to icon and harmonize the close button with the rest