Summary

Following up from PLANET-6747 that we implemented during the IA MVP phase, we can unify the logic of the Posts breadcrumb regardless of the "New IA" feature flag status.

Requirements

• Taxonomy breadcrumbs should follow the new IA logic:
  • Post Type > Category | Category (see screenshot)
• Simplify any involved template code (eg. header, singe).
• Simplify Post class code accordingly.