Add Address Group support for Cloud Armor

[Samir-Cit]

This PR add the support for Cloud Armor on the Address Group resource.
It's the purpose enum field but it's still on beta version.

• A new PR will be needed when this fields is available for GA.

Release Note Template for Downstream PRs (will be copied)

networksecurity: added `purpose` field to `google_network_security_address_group` resource (beta only)

[github-actions]

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@slevenick, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 1 file changed, 20 insertions(+))
google-beta provider: Diff ( 3 files changed, 97 insertions(+))
terraform-google-conversion: Diff ( 1 file changed, 10 insertions(+))

[modular-magician]

Tests analytics

Total tests: 39
Passed tests: 37
Skipped tests: 1
Affected tests: 1

Click here to see the affected service packages

• networksecurity

Action taken

Found 1 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit. Click here to see the affected tests

• TestAccNetworkSecurityAddressGroup_networkSecurityAddressGroupsCloudArmorExample

Get to know how VCR tests work

[modular-magician]

$\textcolor{green}{\textsf{Tests passed during RECORDING mode:}}$
TestAccNetworkSecurityAddressGroup_networkSecurityAddressGroupsCloudArmorExample[Debug log]

$\textcolor{green}{\textsf{No issues found for passed tests after REPLAYING rerun.}}$

---

$\textcolor{green}{\textsf{All tests passed!}}$

View the build log or the debug log for each test

[github-actions]

@slevenick This PR has been waiting for review for 3 weekdays. Please take a look! Use the label disable-review-reminders to disable these notifications.

[slevenick]

Thanks!