Migrate onboarding tour steps to React

Created by: valerybugakov

Context

1. Onboarding tour functionality relies on the shepherd.js library which relies on HTMLElement text property to render tour steps.
2. Most HTML elements for tour steps were created using template string literals.
3. We needed to drop global CSS classes and migrate to our React components because of the Wildcard migration.
4. The renderBrandedToString utility was introduced to enable the migration.

To solve the problem, we need to migrate to a React way of defining tour step content. Here's the related issue mentioned in the utility description: https://github.com/shipshapecode/react-shepherd/issues/612.

Expected behavior

1. The renderBrandedToString utility is removed.
2. Onboarding tour steps are defined using the declarative React approach instead of template string literals.