mgr/dashboard: Introduce NVMe/TCP navigation

mgr/dashboard: Introduce NVMe/TCP navigation

Fixes https://tracker.ceph.com/issues/66346

- adds NVMe/TCP tab under Block nav
- adds overview page for NVMe/TCP nav
- overview page lists gateways
- add default error page when no nvmeof service running
- added unit tests
- fixes service page e2e test

Signed-off-by: Afreen <afreen23.git@gmail.com>
(cherry picked from commit 442346f0efbb5d7d3af3ebdf847586bbe3f93f6d)

Conflicts:
	src/pybind/mgr/dashboard/frontend/src/app/ceph/cluster/services/service-form/service-form.component.html
	src/pybind/mgr/dashboard/frontend/src/app/core/navigation/navigation/navigation.component.html