Allow specifying security settings in casc defaults

[miles-w-3]

Is your feature request related to a problem? Please describe

I would like to be able to specify my own security settings under the security header in jenkins casc. Currently, this is not supported when using the default casc settings that the chart provides, and we want to still be able to use the defaults for agent specifications

Describe the solution you'd like

Add a field to the jenkins.controller values for providing security configs.

Describe alternatives you've considered

Overriding the entire jenkins.casc.defaults helper, but that isn't practical since it contains so much key functionality that may be changed by the chart.

Additional context

No response