[APIGW]: groups resource

[artem-lifshits]

Summary of the Pull Request

Resource for group management implemented

PR Checklist

• Refers to: Adding new service API-Gateway to terraform provider #2403
• Tests added/passed.
• Documentation updated.
• Schema updated.
• Release notes added.

Acceptance Steps Performed

=== RUN   TestAccAPIGWv2Group_basic
=== PAUSE TestAccAPIGWv2Group_basic
=== CONT  TestAccAPIGWv2Group_basic
--- PASS: TestAccAPIGWv2Group_basic (393.53s)
PASS

Process finished with the exit code 0

=== RUN   TestAccAPIGWGroupV2ImportBasic
--- PASS: TestAccAPIGWGroupV2ImportBasic (398.73s)
PASS

Process finished with the exit code 0

[otc-zuul]

Build succeeded.
https://zuul.otc-service.com/t/eco/buildset/dd5c9780804e43e5bec8b13cd0f6e631

✔️ build-otc-releasenotes SUCCESS in 7m 26s
✔️ noop SUCCESS in 0s
✔️ otc-golangci-lint SUCCESS in 3m 11s
✔️ golang-make-test SUCCESS in 4m 28s
✔️ golang-make-vet SUCCESS in 3m 48s
✔️ tflint SUCCESS in 2m 53s
✔️ goreleaser-build SUCCESS in 7m 00s
✔️ otc-terraform-visualize-main SUCCESS in 6m 21s