`nns get-records` and `nns tokens` command do not need to sign anything,
so remove useless actor and use invoker directly.
`NewLocalActor()` is only used in `ape` and `nns` packages. `ape`
package seem to use it correctly, only when alphabet wallets are
provided, so no changes there.
Also, remove --alphabet-wallets flag from commands that do not need it.
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
