Review and fix inconsistencies caused by flags not checked by anr

[felipemadero]

Eg setting staking-tls-key-contents as a flag via RPC should be denied as ANR takes ownership of the file generation. The setting should be configurable by passing a node config, and be managed by ANR.
That is, either allow only one way to configure the settings managed by ANR, or add logic to allow all ways.