Blade nav filter + groups

Azure resource-menu parity: a search box filtering the left blade menu, and collapsible group headers (Settings / Monitoring / …).

Why deferred

Our deepest type has a handful of blades — a filter over a handful of items and groups of one are pure chrome.

Revisit when

Any type approaches ~8+ blades (e.g. activity log + publish history + tags-as-blade stacking up), which is when the portal's menu furniture starts paying for itself.