Apply Kiso theme colors for the Drupal core Toolbar module

[smillart]

Classes of the Drupal core Toolbar module templates need to be upgraded to the Drupal "Kiso" (基礎) base theme stylesheets guidelines which are based on the Drupal CSS coding standards and best practices (BEM Methodology) regarding the formatting of class names:

/* BEM for Block, Element & Modifier */
.block { ... }
.block__element { ... }
.block__element--modifier { ... }

/* Drupal components class naming convention */
/* @file template-name.html.twig / template-name.(s)css */
.template-name { ... }
.template-name--variant { ... }
.template-name__sub-object { ... }
.template-name__sub-object--variant { ... }

/* Administrative toolbar class names formatting */
/* @file toolbar.html.twig / toolbar.(s)css */
.toolbar { ... }
.toolbar__bar { ... }
.toolbar__tab { ... }

/* Administrative toolbar menu class names formatting */
/* @file menu--toolbar.html.twig / menu--toolbar.(s)css */
.menu--toolbar { ... }
.menu--toolbar .menu__item { ... }
.menu--toolbar .menu__item--expanded { ... }
.menu--toolbar .menu__item--collapsed { ... }