Select color theme according to current color theme in dev mode

[harbin1053020115]

When developing extensions with color themes, the VS Code will initialize the color theme with the first color theme defined in the extension's package.json. The code shows as below:

As I want to switch to anthor color theme and refresh browser page to debug anthor color theme, it seems only to switch the color theme again after the browser page refreshed.

[aeschli]

Verify by:

• create a theme extension ( use yo code)
• in the theme extension define a light and a dark theme
• run the extension.
• Verify that VS Code window that opens has the theme in development open that matches the current color scheme