Add support for opt-in avatar on every step of the breadcrumb component

Problem

Following the dicsussion in !387 (comment 199608310), the initial breadcrumb component implemented does not support opt-in avatar on every step of the breadcrumb. Since the current implementation of the breadcrumb hides or shows the avatar per need, adding support for opt-in avatar on every step of the breadcrumb component could help make this more useful.

Proposal

Let's add support for opt-in avatar on every step of the breadcrumb.