Enhancement: VS Code theme support for the dashboards

[estruyf]

Bring Visual Studio Code theme support to the dashboards. This would also solve the issue with high contrast mode #485

[estruyf]

This will be implemented as an experimental feature to see which themes work and which fail.

If the experimental mode is turned on, the VSCode theme colors are used; otherwise, it keeps using the default colors.

Once we have a good mapping for all controls, we could make the whole switch.

[michaeltlombardi]

Looking forward to testing this out!

[estruyf]

Todo:

• Contents
• Data view
• Error view
• Header
• Layouts
• Media view
• Menu
• Modals
  • Alert
  • Form
  • Info
• Preview
• Snippets view
• Steps
• Taxonomy view
• Unknown view
• Welcome screen
• Other files
• CSS Data fields

[estruyf]

Here are a couple of WIP screenshots