feat: add support for conditional creation and association of network security groups

[lixhunter]

Description

PR Checklist

• I have checked if my changes close any open issues. If so please include appropriate closing keywords below.
• I have updated/added documentation written in a helpful and kind way to assist users that may be unfamiliar with the resource / data source.
• I have checked for a proper tag for this PR: breaking-change, feature, fix, other, ignore-release
• I have used a meaningful PR title to help maintainers and other users understand this change and help prevent duplicate work.

Motivation and Context

Feedback from @matthiasbretag:

But we have a new issue. For some reason, network security groups are created now for each NIC which is not a behavior we want or require. Would you please check and make another change so this gets fixed. I believe this behavior might have been introduced with one of the prior versions, probably v1.8.0.

With the adjustments below one should set the following parameter;

create_network_security_group  = false

and this should prevent the creation of NSGs.

Breaking Changes

[HelenaSeidel]

imo ok