feat(workspace): add new data source to query associated desktop pools for users

[Lance52259]

What this PR does / why we need it:

Supports a new data source that used to query associated desktop pools for specified users.

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 data source to query associated desktop pools for users

PR Checklist

• Tests added/passed.

./scripts/coverage.sh -o workspace -f TestAccDataUserDesktopPoolAssociations_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 TestAccDataUserDesktopPoolAssociations_basic -timeout 360m -parallel 10
=== RUN   TestAccDataUserDesktopPoolAssociations_basic
--- PASS: TestAccDataUserDesktopPoolAssociations_basic (367.01s)
PASS
coverage: 9.0% of statements in ./huaweicloud/services/workspace
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/workspace 367.093s        coverage: 9.0% 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 <<<<<<

[github-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This PR has been approved by: @Lance52259

[Lance52259]

./scripts/coverage.sh -o workspace -f TestAccDataUserDesktopPoolAssociations_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 TestAccDataUserDesktopPoolAssociations_basic -timeout 360m -parallel 10
=== RUN   TestAccDataUserDesktopPoolAssociations_basic
--- PASS: TestAccDataUserDesktopPoolAssociations_basic (367.52s)
PASS
coverage: 9.0% of statements in ./huaweicloud/services/workspace
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/workspace 367.609s        coverage: 9.0% of statements in ./huaweicloud/services/workspace

[github-ci-robot]

This PR needs rebase.