SWF-Editor: Dark theme support

[handreyrc]

Summary

The goal of this task is to add theme support to the editor.
Initialy the editor shall support light and dark themes.

Note: The API to set theme shall work the same way as it works in the current implementation of the editor otherwise it won't be compatible with VsCode plugin and the combined editor. Follow the same color patterns of the current dark theme implementation.

Description

• Implement and expose an API to set themes (applyTheme()).
• Create a centralized theme configuration.
• Add theme configuration support in the inialization of the editor.
• The theme should be applied to all internal canvas elements.
• If no theme is set in the initialization, the light theme shall be set by default.
• Themes shall be also applied to the error page.

Testing

Run the component and open a valid worflow.
Open the console and call the API to set a theme theme, "applyTheme([light / dark])", and check if the theme was properly applied to all internal canvas elements.

Dependencies

• SWF-Editor: Marshallers JSON / YAML as an external lib  #1653
• SWF-Editor: Error icon and error popups #1656
• SWF-Editor: Selection manager #1658
• SWF-Editor: Highlight manager #1659
• SWF-Editor: Enable Zoombar #1663
• SWF-Editor: Enable Preview component #1664
• SWF-Editor: Export workflow to svg #1665