[FEATURE] Support change admin password

[ylwu-amzn]

Is your feature request related to a problem?

I don't see how to change admin password from the readme. For security enabled cluster, the default password for admin is too weak (it's admin by default). Seems we have no way to change the default password for admin now.

What solution would you like?

Provide some option to let user specify their own password

What alternatives have you considered?

No

Do you have any additional context?

No

[rishabh6788]

This feature comes from Security plugin, will go through the existing code and try to figure out if the user details can be updated at cluster setup.

[rishabh6788]

This PR should address this concern as users will be able to provide the configuration using additionalConfig flag.