feat(theme): add high contrast theme poc

packages/react-core/src/demos/HighContrast.md

@@ -0,0 +1,32 @@
+---
+id: High contrast
+section: patterns
+---
+
+import CheckCircleIcon from '@patternfly/react-icons/dist/js/icons/check-circle-icon';
+import InfoCircleIcon from '@patternfly/react-icons/dist/js/icons/info-circle-icon';
+import CodeIcon from '@patternfly/react-icons/dist/esm/icons/code-icon';
+import CodeBranchIcon from '@patternfly/react-icons/dist/esm/icons/code-branch-icon';
+import CubeIcon from '@patternfly/react-icons/dist/esm/icons/cube-icon';
+import FilterIcon from '@patternfly/react-icons/dist/esm/icons/filter-icon';
+import SortAmountDownIcon from '@patternfly/react-icons/dist/esm/icons/sort-amount-down-icon';
+import EllipsisVIcon from '@patternfly/react-icons/dist/esm/icons/ellipsis-v-icon';
+import display from '@patternfly/react-styles/css/utilities/Display/display';
+import sizing from '@patternfly/react-styles/css/utilities/Sizing/sizing';
+import spacing from '@patternfly/react-styles/css/utilities/Spacing/spacing';
+import { DashboardWrapper } from '@patternfly/react-core/dist/js/demos/DashboardWrapper';
+
+import MagicIcon from '@patternfly/react-icons/dist/esm/icons/magic-icon';  
+import CogIcon from '@patternfly/react-icons/dist/esm/icons/cog-icon';
+import HelpIcon from '@patternfly/react-icons/dist/esm/icons/help-icon';
+import BellIcon from '@patternfly/react-icons/dist/esm/icons/bell-icon';
+import QuestionCircleIcon from '@patternfly/react-icons/dist/esm/icons/question-circle-icon';
+import BarsIcon from '@patternfly/react-icons/dist/esm/icons/bars-icon';
+import ExclamationCircleIcon from '@patternfly/react-icons/dist/esm/icons/exclamation-circle-icon';
+import { useState } from 'react';
+
+### High contrast
+
+```js file='./examples/HighContrast/HighContrast.tsx' isFullscreen
+
+```