nethsecurity-controller: improve configuration form

[gsanchietti]

Improve the current form with these changes:

• make sure the user understands that the password can't be changed later from the main UI
• move retention options and controller name under an advanced section

See also

Community discussion: https://community.nethserver.org/t/nethserver-controller-nethsecurity-glitch/23814

[stephdl]

QA

install ghcr.io/nethserver/nethsecurity-controller:0.0.22-dev.2

verify some steps

• the information banner warns you to save the password, only when you are not configured
• the advanced menu is here to hide not important settings
• no expected errors when you configure the module