fix(theme-builder): update theme builder and core styles (#13997)

* theme-builder wip

* Theme Builder updates
- new CSS variable support
- realtime color updating with alpha support (rgb generation)
- auto tint/shade/contrast generation
- auto step generation
- CSS variable highlighting (forward and backwards)
- Colourlovers Palette search (via local proxy)

* Theme Builder Updates
- Settings for auto generation
- updated to 10 steps per background/ext
- general cleanup
- added instructions
- re-worked shade/tint to mix black and white instead of lighten/darken
- scoped cssText into component
- apply theme to theme builder also to style internal buttons

SCSS Updates
- added 10 steps to reach platform
- updated SCSS to use same mix and color methods as theme builder

* material design color step fix

* readme files

fixes #13985 fixes #13986

packages/core/src/components/slides/slides.ios.vars.scss

@@ -1,7 +1,7 @@
 @import "../../themes/ionic.globals.ios";
 
 /// @prop - Slides Bullet Background color
-$slides-ios-bullet-background-color:              text-ios-color-step-200 !default;
+$slides-ios-bullet-background-color:              $text-ios-color-step-400 !default;
 
 /// @prop - Slides Bullet Background color when Active
 $slides-ios-bullet-background-color-active:       ion-color($colors-ios, primary, base, ios) !default;

packages/core/src/components/slides/slides.md.vars.scss

@@ -1,7 +1,7 @@
 @import "../../themes/ionic.globals.md";
 
 /// @prop - Slides Bullet Background color
-$slides-md-bullet-background-color:               $text-md-color-step-200 !default;
+$slides-md-bullet-background-color:               $text-md-color-step-400 !default;
 
 /// @prop - Slides Bullet Background color when Active
 $slides-md-bullet-background-color-active:        ion-color($colors-md, primary, base, md) !default;