feat(workspace/app): the APP server group supports to modify tags

[wuzhuanhong]

What this PR does / why we need it:

The Workspace App server group supports to update tags.

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:

PR Checklist

• Tests added/passed.

./scripts/coverage.sh -o workspace -f TestAccResourceAppServerGroup_singleSession
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 TestAccResourceAppServerGroup_singleSession -timeout 360m -parallel 10
=== RUN   TestAccResourceAppServerGroup_singleSession
=== PAUSE TestAccResourceAppServerGroup_singleSession
=== CONT  TestAccResourceAppServerGroup_singleSession
--- PASS: TestAccResourceAppServerGroup_singleSession (44.65s)
PASS
coverage: 5.2% of statements in ./huaweicloud/services/workspace
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/workspace 44.801s coverage: 5.2% of statements in ./huaweicloud/services/workspace

• Documentation updated.

• Schema updated.

• CheckDeleted.

  • a. During query operation (Read Context)
    aa. Resource not found
    >>>>>> Paste the screenshot here <<<<<<

  • b. During delete/disassociate/unbind operation (Delete Context)
    ba. Resource not found
    >>>>>> Paste the screenshot here <<<<<<