feat(workspace/app_group): add application group resource

[wuzhuanhong]

What this PR does / why we need it:

Add new resource supports APP group. Add corresponding client in the endpoints.go file.

Which issue this PR fixes: (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged) fixes #xxx

Special notes for your reviewer:

Release note:

1. add new resource.
2. add corresponding to document and acceptance test.

PR Checklist

• [x] Tests added/passed.

/scripts/coverage.sh -o workspace -f TestAccResourceWorkspaceAppGroup_basic
Prepare to calculate the coverage the following command:
TF_ACC=1 go test "./huaweicloud/services/acceptance/workspace" -v -coverprofile="./huaweicloud/services/acceptance/workspace/workspace_coverage.cov" -coverpkg="./huaweicloud/services/workspace" -run TestAccResourceWorkspaceAppGroup_basic -timeout 360m -parallel 10
=== RUN   TestAccResourceWorkspaceAppGroup_basic
=== PAUSE TestAccResourceWorkspaceAppGroup_basic
=== CONT  TestAccResourceWorkspaceAppGroup_basic
--- PASS: TestAccResourceWorkspaceAppGroup_basic (30.42s)
PASS
coverage: 6.0% of statements in ./huaweicloud/services/workspace
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/workspace 30.470s coverage: 6.0% of statements in ./huaweicloud/services/workspace

• [x] Documentation updated.

• [x] Schema updated.

• [x] CheckDeleted.

  • a. During query operation (Read Context) aa. Resource not found

  • b. During delete/disassociate/unbind operation (Delete Context) ba. Resource not found