Move native color styles from the color-modes bundle to the base bundle

.changeset/fair-cups-lay.md

@@ -0,0 +1,5 @@
+---
+"@primer/css": minor
+---
+
+Move native color styles from the color-modes bundle to the base bundle

src/base/index.scss

@@ -1,4 +1,5 @@
 @import '../support/index.scss';
+@import './native-colors.scss';
 @import './normalize.scss';
 @import './base.scss';
 @import './kbd.scss';

src/color-modes/index.scss

@@ -9,4 +9,3 @@
 @import './themes/dark_high_contrast.scss';
 @import './themes/dark_colorblind.scss';
 @import './themes/dark_tritanopia.scss';
-@import './native.scss';