Added a `register` method to `NodeActor` following the same pattern used
by other actors in the devtools codebase. Updated
`NodeInfoToProtocol::get_or_register_node_actor` to use it instead of
constructing `NodeActor` directly.
Testing:
Ran `./mach try linux-unit-tests` and `./mach test-devtools`. No new
failures introduced.
Fixes:part of #43800
---------
Signed-off-by: Emmanuel Paul Elom <elomemmanuel007@gmail.com>