Add optional breadcrumb navigation to WordPress admin area

[samahjoob12]

The WordPress admin interface lacks a built-in breadcrumb navigation system. As the admin menu grows more complex with nested pages (especially from plugins and themes), it's increasingly easy for users to lose track of their location or struggle to navigate back efficiently.

This proposal introduces a lightweight, optional breadcrumb trail displayed at the top of admin pages — just beneath the admin bar and above the page title.

Example Display:

For the Permalinks settings page, the breadcrumb could look like:

Dashboard > Settings > Permalinks

Each segment would be a clickable link, except the last item which reflects the current page.

Behavior:

Breadcrumbs are generated dynamically based on the admin menu hierarchy ($menu, $submenu) and current screen.

Default is enabled for all users.

Optional toggle under Users → Profile to disable breadcrumbs for individual users.

Developers can filter or modify breadcrumbs using a new filter: admin_breadcrumbs.

Benefits:

Improved UX, especially for users navigating unfamiliar admin screens (e.g., plugin settings).

Helps users understand admin page hierarchy and find their way back quickly.

Promotes consistency and predictability in admin navigation.

Why it belongs in Core:

No current core support for admin breadcrumbs.

Plugins often reimplement their own breadcrumbs inconsistently.

This is a small, self-contained improvement that significantly improves admin usability with minimal overhead.