Fixed some issues with light theme support:
1) Icons in content tree nodes (Folder icons) now use the foreground color. I did not find a case where the content tree is used for other icons.
2) The asset picker now uses the Background Normal color (instead of a very transparent dark gray) for the background, and Orange for the text. Did not seem like it warranted adding a new color, and Orange works in both dark and light styles.
3) The platform selector icons are now hard-coded instead of based on the style. This may sound odd, but the icons are colored, so they should always use White as the fully active color. Previously they worked with a dark theme because the Foreground was set to white.
4) Fixed the CollectionBackgroundColor in the light theme being dark gray instead of light gray like it should be. This fixes certain lists of things having a dark background in the light theme.
1) Added ForegroundViewport as a new color. It is used in the main game viewport (ViewportWidgetButton), and the viewport for rendering of particles and materials. It is needed because the default foreground in a Light theme is black, but black does not work well in a viewport. A new color seemed appropriate.
2) Fixed the profiler window to use the Foreground color in multiple text elements, instead of Color.White (or no default TitleColor). This includes the Row class, Asset class, SingleChart class, Timeline Class, and more.
3) Added a second theme/Style (DefaultLight) to include with the engine. It uses RGB float values because those were easier to transfer from the saved values that I had created (and they're easier for me to edit if necessary). I tried to emulate how the Default theme is created/loaded/etc as closely as possible.
