mount method
Hands everything under path to handler.
The counterpart to shelf_router.mount and axum's nest_service. The
handler sees paths relative to path, so a shelf_static handler, or
any other framework's handler, works unchanged:
app.mount('/assets', createStaticHandler('public'));
mount('/') claims every path, which is how a single-page build is
served. Declare the routes that must win above it: the first declaration
that matches is the one that runs, and that counts route, mount, and
nest alike, in the order they were written.
Implementation
void mount(String path, Handler handler) {
_requireOpen();
final route = Route.mount(normalizePrefix(path), handler);
internals.routes.add(route);
internals.declarations.add(route);
}