fix(bundle): align the web debug toolbar item with the Symfony core styles

The collector item used `sf-toolbar-status` for its label, which renders it
on a grey badge instead of the plain value styling used by the core items,
and shipped a colourful base64 PNG borrowed from the jwt.io logo instead of
an outlined icon.

The PNG is replaced by a Tabler outline SVG following the same conventions as
the icons of the WebProfilerBundle (24x24, 1.5 stroke width, `currentColor`),
so the item now inherits the toolbar colours in both light and dark themes.

Fixes #663

Author: Spomky