Add id attribute to azuredevops_groups datasource

[favoretti]

All Submissions:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code follows the code style of this project.
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What about the current behavior has changed?

Issue Number:

Does this introduce a change to go.mod, go.sum or vendor/?

• Yes
• No

Does this introduce a breaking change?

• Yes
• No

Any relevant logs, error output, etc?

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Other information

Same as azuredevops_users datasource - expose StorageKey descriptor value as an id attribute of groups collection.

[favoretti]

@xuzhang3 mind having a look please? Thank you!

[xuzhang3]

=== RUN   TestAccGroupsDataSource_Read_Project
=== PAUSE TestAccGroupsDataSource_Read_Project
=== RUN   TestAccGroupsDataSource_Read_NoProject
=== PAUSE TestAccGroupsDataSource_Read_NoProject
=== CONT  TestAccGroupsDataSource_Read_Project
=== CONT  TestAccGroupsDataSource_Read_NoProject
--- PASS: TestAccGroupsDataSource_Read_NoProject (38.43s)
--- PASS: TestAccGroupsDataSource_Read_Project (64.27s)
PASS
ok      github.com/microsoft/terraform-provider-azuredevops/azuredevops/internal/acceptancetests        82.132s