tenable.{io,nessus} does not support agent settings API endpoint

[dsobon]

Is your feature request related to a problem? Please describe.

Currently it is not possible to update agent settings through the module.

Describe the solution you'd like

For both modules to support "agent_settings" update API endpoint:

• Nessus Manager: /agents/settings
• Tenable.IO: /scanners/null/agents/_bulk/directive

I guess it should be contained within "Agent Config"... or for it to be renamed to "Agent Settings" (backend name?)

Describe alternatives you've considered

I have considered bypassing the module and making the API calls directly, but that's just a workaround.