node-proxy: introduce component spec registry and overrides for updates

node-proxy: introduce component spec registry and overrides for updates

This change introduces a single COMPONENT_SPECS dict and get_update_spec(component)
as the single source of truth for RedFish component update config (collection, path,
fields, attribute). To support hardware that uses different paths or attributes,
get_component_spec_overrides() allows overriding only those fields (via dataclasses.replace())
without duplicating the rest of the spec.
All _update_network, _update_power, etc. now call _run_update(component).

For instance, AtollonSystem uses this to set the power path to 'PowerSubsystem'.

Fixes: https://tracker.ceph.com/issues/74749
Signed-off-by: Guillaume Abrioux <gabrioux@ibm.com>